Colon, Rectum and Anus Flashcards

Question

A 57-year-old male develops urinary retention after an uncomplicated hemorrhoidectomy. A foley is placed to decompress the bladder. What is the MOST likely cause of his urinary retention? A. Local anesthesia B. Muscle spasms C. Inadequate resuscitation D. Pelvic splanchic nerve damage E. Loss of bladder tone

Answer 1

B. Muscle spasms

Answer 2

Hindgut begins at distal third of the transverse colon and extends to the rectum

Answer 3

Inferior mesenteric artery

Answer 4

The lateral peritoneal reflections of the ascending and descending colon

Answer 5

Esophagus, middle, and distal rectum

Answer 6

The small bowel is smooth, whereas the colon has fat appendages (appendices epiploicae), haustra, and taenia coli

Answer 7

Proximal: superior hemorrhoidal artery (superior rectal artery) from the inferior mesenteric artery Middle: middle hemorrhoidal artery (middle rectal artery) from the hypogastric artery (internal iliac artery) Distal: inferior hemorrhoidal artery (inferior rectal artery) from the pudendal artery, which is a branch of hypogastric artery (internal iliac artery)

Answer 8

Proximal: inferior mesenteric vein that joins the splenic vein to drain into the portal vein Middle: iliac vein into the inferior vena cava Distal: iliac vein into inferior vena cava

Answer 9

Water, sodium, and bile salt absorption and stool storage

Answer 10

Short-chain fatty acids (SCFAs) (butyrate)

Answer 11

12 to 15 cm

Answer 12

Anal canal: 0 to 5 cm Rectum: 5 to 15 cm Rectosigmoid junction: 15 to 18 cm

Answer 13

The distal point at which the taeniae converge at the level of the sacral promontory

Answer 14

Anatomists: dentate line Surgeons: proximal border of the anal sphincter complex

Answer 15

Pouch of Douglas (Ehrhardt-Cole recess/ rectouterine excavation/ rectouterine pouch)

Answer 16

Pouch of Douglas

Answer 17

Denonvilliers fascia

Answer 18

Blumer’s shelf

Answer 19

Waldeyer fascia (rectosacral fascia)

Answer 20

The middle rectal artery

Answer 21

Pubococcygeus, iliococcygeus, puborectalis (which form the levator ani)

Answer 22

Between the pubis, obturator fascia, sacrum, and ischial spines

Answer 23

The marginal artery of Drummond

Answer 24

The arc of Riolan (meandering mesenteric artery)

Answer 25

Left colic artery

Answer 26

Right and proximal transverse colon drain into the superior mesenteric vein, which joins with the splenic vein to become the portal vein Distal transverse colon, descending colon, sigmoid, and most of the rectum drain into the inferior mesenteric vein, which drains into the splenic vein that joins with the superior mesenteric vein to become the portal vein Anal canal drains by way of the middle and inferior rectal veins into the internal iliac veins, which drain into the inferior vena cava

Answer 27

Para-aortic nodal chain

Answer 28

Para-aortic nodal chain or superficial inguinal nodal chain

Answer 29

Severing of the hypogastric nerves near the sacral promontory

Answer 30

Injury to the mixed parasympathetic and sympathetic periprostatic plexus

Answer 31

Bacteroides species

Answer 32

Escherichia coli

Answer 33

>3 loose stools/day

Answer 34

<3 stools/wk

Answer 35

Complete bowel obstruction, free perforation

Answer 36

Mucosa herniates through the colon at sites of penetration of the muscular wall by arterioles on the side of the antimesenteric taeniae

Answer 37

Sigmoid colon (80%)

Answer 38

Sigmoid colon

Answer 39

Antibiotics on an outpatient basis; if patient has significant pain (localized peritonitis), admit to the hospital and give intravenous (IV) antibiotics for -48 hours

Answer 40

After symptoms have subsided for at least 3 weeks, a colonoscopic examination should be performed to establish the presence/location of the diverticula and to exclude cancer (mimics diverticulitis)

Answer 41

Young patients with an episode of diverticulitis ( <45 years old), patients with 2 episodes of diverticulitis, and immunocompromised patients

Answer 42

The preferred treatment is computed tomography (CT) or ultrasound-guided percutaneous drainage or drainage of a pelvic abscess into the rectum through a transanal approach followed by elective surgery -6 weeks after drainage of the abscess, when the patient has completely recovered from the infection, versus a more undesirable transabdominal approach by laparotomy

Answer 43

A perforated diverticulum into the peritoneal cavity that is not sealed by the body's normal defenses; an initially localized abscess that expands and suddenly bursts into the peritoneal cavity

Answer 44

A Hartmann procedure: resection of the diseased sigmoid colon; creation of a descending colostomy using noninflamed tissue; closure of the divided end of the rectum with suture/ staples

Answer 45

At least 10 weeks (when patient has completely recovered from their illness)

Answer 46

Stage I: diverticulitis with associated pericolic abscess Stage II: diverticulitis associated with distant abscess (retroperitoneal or pelvic) Stage III: diverticulitis associated with purulent peritonitis Stage IV: diverticulitis associated with fecal peritonitis

Answer 47

Sigmoid colon

Answer 48

Transverse colon

Answer 49

The cecum folds anteromedial to the ascending colon from the presence of a constricting band across the ascending colon

Answer 50

Plain film: bent inner tube with apex in the right upper quadrant CT scan: mesenteric whorl Barium enema: bird's beak deformity

Answer 51

Appropriate resuscitation; decompression with placement of a soft rectal tube through the proctoscope past the twist of the volvulus and leaving the rectal tube in place. If a rectal tube cannot be passed, detorsion of the volvulus with a colonoscope. If unable to detorse volvulus by rectal tube or colonoscopy, perform Hartmann operation procedure. Confirm the reduction with an abdominal radiograph, attempt a full colonoscopic examination after cleansing the bowel with cathartics, perform an elective sigmoid colon resection.

Answer 52

An axial rotation of the terminal ileum, cecum, and ascending colon with concomitant twisting of the associated mesentery from a lack of fixation of the cecum to the retroperitoneum

Answer 53

A gas-filled comma shape with the concavity facing inferiorly and to the right (upsidedown comma sign), a circular shape with. a narrow, triangular density pointing to the right and superiorly, a dilated cecum displaced to the left side of the abdomen

Answer 54

The procedure of choice is a right colectomy with primary anastomosis; if frankly gangrenous bowel, resect right colon and create an ileostomy; cecopexy is another option (higher recurrence rates)

Answer 55

Colorectal cancer

Answer 56

Colonic volvulus (high-fiber diets)

Answer 57

An obstruction featuring the occlusion of the proximal and distal parts of the bowel

Answer 58

Ogilvie syndrome

Answer 59

Water-soluble contrast enema can reliably differentiate between mechanical obstruction and pseudo-obstruction; can consider colonoscopy

Answer 60

Initial treatment with nasogastric decompression, fluid replacement, correction of electrolyte abnormalities, discontinuation of all medications that inhibit bowel motility, serial abdominal examinations and radiographs; consider administration of 2.5 mg of neostigmine given intravenously over 3 minutes after ruling out distal obstruction with water-soluble contrast enema or colonoscopy (do not give to patients with significant cardiac history, and watch for bradycardia by monitoring patient with telemetry during administration of the drug with atropine immediately available); can consider colonoscopic decompression, but high recurrence

Answer 61

Tension is directly proportional to increased pressure times radius. Stated differently, for a given pressure, increased radius requires increased wall thickness to accommodate a stable wall tension; also, increased pressure requires increased thickness to maintain a stable wall tension. It is remembered by the following equation: T = Yi (P x R)/t (T =wall tension, P =pressure, R =radius, T =wall thickness) The law explains why the cecum, with its largest diameter, is the most common site of colonic rupture secondary to distal obstruction or increased pressure (e.g., overzealous insuftlations with excessive air during colonoscopy).

Answer 62

Mucosa and submucosa

Answer 63

Rectal involvement (proctitis)

Answer 64

Continuous, uninterrupted inflammation of the colonic mucosa beginning in the distal rectum and extending proximally Crohn disease features normal segments of colon [skipped areas] interspersed between distinct segments of colonic inflammation), ulcerative colitis does not involve the terminal ileum, except with backwash ileitis; ulcerative colitis affects the mucosa and submucosa, where Crohn disease can have transmural involvement.

Answer 65

Stricture appears later in the course of ulcerative colitis; stricture is proximal to the splenic flexure and causes large-bowel obstruction

Answer 66

Arthritis, ankylosing spondylitis, erythema nodosum, pyodenna gangrenosum, primary sclerosing cholangitis

Answer 67

Primary sclerosing cholangitis, ankylosing spondylitis

Answer 68

Colonoscopy every 1 to 2 years beginning 8 years after the onset of pancolitis 12 to 15 years after the onset of left-sided colitis

Answer 69

Aminosalicylates (sulfasalazine, mesalamine) Corticosteroids (prednisone) Immunosuppressive agents ( azathioprine, cyclosporine)

Answer 70

``` Dysplasia carcinoma, long-standing disease, intractability, massive colonic bleeding, toxic megacolon (may consider surgery for malnutrition/growth retardation in pediatric/ adolescent patients), persistent obstruction or stricture, perforation ```

Answer 71

Nasogastric decompression; IV hydration (with consideration given to IV hyperalimentation depending on length of illness before fulminant episode and patient's nutritional status); broad-spectrum IV antibiotics; high-dose IV steroids if patient is steroid-dependent; follow with serial abdominal exams and leukocyte counts; if deteriorates or if lack of improvement with medical therapy for 24 to 48 hours, perform an urgent procedure

Answer 72

Total abdominal colectomy with ileostomy and preservation of the rectum

Answer 73

Subtotal colectomy; if severe bleeding from rectal mucosa, may also require emergency proctectomy

Answer 74

Total proctocolectomy with ileostomy; restorative proctocolectomy with ileal pouch anal anastomosis; total proctocolectomy with a continent ileal reservoir (Kock pouch)

Answer 75

``` Cancer Fistula Growth retardation Intraabdominal abscess Intractability Toxic megacolon Massive bleeding Intestinal obstruction ```

Answer 76

Abdominal colectomy and ileostomy versus ileorectal anastomosis if the rectum is not inflamed

Answer 77

Campylobacter jejuni, Yersinia enterocolitica, Salmonella typhi, Clostridium difficile

Answer 78

Colonic ischemia

Answer 79

Thumb printing

Answer 80

Splenic flexure and rectosigmoid junction (Griffith and Sudeck point)

Answer 81

Peritoneal signs, massive bleeding, universal fulminant colitis with or without toxic megacolon

Answer 82

3-2-1: At least 3 first-degree relatives with colon cancer and all of the following: * 2 successive generations affected * At least 1 case of colon cancer diagnosed before age 50 years; familial adenomatous polyposis excluded

Answer 83

The modified Amsterdam criteria is almost the same as the Amsterdam criteria, except that with the modified Amsterdam criteria the cancer must be associated with HNPCC (colon, endometrium, small bowel, ureter, renal pelvis) instead of specifically colon cancer

Answer 84

Colonoscopy at age 20 to 25 years and repeat every 1 to 3 years Transvaginal ultrasound or endometrial aspirate at age 20 to 25 years and repeat annually

Answer 85

A detailed family history

Answer 86

Abdominal colectomy with ileorectal anastomosis If the patient is female with no further plans for childbearing, prophylactic total abdominal hysterectomy and bilateral salpingo-oophorectomy are recommended

Answer 87

Flexible proctosigmoidoscopy at age 10 to 12 years and repeat every 1 to 2 years until age 35; after age 35 repeat every 3 years Upper GI endoscopy every 1 to 3 years starting when polyps are first identified.

Answer 88

Restorative proctocolectomy with ileal pouch anal anastomosis with distal rectal mucosectomy Alternative includes total abdominal colectomy with ileorectal anastomosis.

Answer 89

Yes, because the duodenal and ampullary polyps are usually neoplastic All large polyps should be removed with endoscopic polypectomy, and pancreatoduodenectomy (Whipple procedure) is indicated with ampullary cancer discovered at an early stage.

Answer 90

10 juvenile polyps

Answer 91

Hyperplastic polyps

Answer 92

No, but adenomatous changes can be found in hyperplastic polyps

Answer 93

Peutz-Jeghers syndrome

Answer 94

False; Peutz-Jeghers syndrome is associated with an increased risk for cancer throughout the intestinal tract, from the stomach to the rectum, and extraintestinal malignancies (breast, ovary, cervix, fallopian tubes, thyroid, lung, gallbladder, bile ducts, pancreas, testicles)

Answer 95

Chromosome 5q21

Answer 96

Tumor suppressor gene

Answer 97

Chromosome 17p

Answer 98

Chromosome 12

Answer 99

Colonoscopy

Answer 100

A water-soluble contrast enema

Answer 101

Right colectomy with primary anastomosis between the ileum and the transverse colon

Answer 102

Right hemicolectomy

Answer 103

Extended right hemicolectomy

Answer 104

Left hemicolectomy

Answer 105

Sigmoidectomy

Answer 106

Patients with multiple primary tumors Individuals with HNPCC Occasionally for patients with completely obstructing sigmoid cancers

Answer 107

Carcinoma in situ: intraepithelial or invasion of lamina propria

Answer 108

Tumor invades submucosa

Answer 109

Tumor invades muscularis propria

Answer 110

Tumor invades through the muscularis propria into the subserosa or into nonperitonealized pericolic or perirectal tissues

Answer 111

Tumor directly invades other organs or structures and/or perforates the visceral peritoneum

Answer 112

No regional lymph node metastasis

Answer 113

Metastasis in 1 to 3 regional lymph nodes

Answer 114

Metastasis in 4 or more regional lymph nodes

Answer 115

No distant metastasis

Answer 116

Distant metastasis

Answer 117

Tis, N0, M0

Answer 118

Tl, NO, MO; T2, NO, MO

Answer 119

Tl to T2, N1, MO

Answer 120

T3 to T4, N1, MO

Answer 121

AnyT,N2,MO

Answer 122

Any T, any N, Ml

Answer 123

Attempt to resect the isolated hepatic/pulmonary metastasis

Answer 124

Stage 3 colon cancer

Answer 125

Oxaliplatin, 5-fluorouracil, leucovorin regimen

Answer 126

Capecitabine (an oral fluoropyrimidine)

Answer 127

A monoclonal antibody that is a vascular endothelial growth factor inhibitor

Answer 128

A monoclonal antibody that binds to and inhibits the epidermal growth factor receptor (EGFR)

Answer 129

Answer: B. Inflammatory bowel disease is associated with an increased risk of colorectal cancer, but there is no association with irritable bowel syndrome. Other factors associated with increased risk are a low intake of dietary fiber and a high intake of red meat. Risk has been shown to be reduced by regular ingestion of aspirin.

Answer 130

Answer: C. Surgery for liver metastases from colorectal cancer is associated with a 2% mortality, can be performed if more than I lesion is present, and is associated with 16% to 40% 5-year survival. Radiotherapy is not used for liver metastases, as the toxicity to normal liver tissue would be too severe.

Answer 131

Answer: A. Bevadzumab is a monoclonal antibody that targets VEGF. It has been shown to improve survival in the metastatic setting when used in combination with chemotherapy.

Answer 132

Answer: C. Carcinoma of the colon afilicts patients with ulcerative colitis 7 to 30 times more frequently than it does the general population. The risk of colon cancer in ulcerative colitis is related to 2 factors: (1) duration of the colitis and (2) extent of colonic involvement The risk of colon cancer for patients who have had the disease less than 10 years is low, but this risk steadily increases. The cancer risk for patients who have had disease activity for 10 to 20 years is 23 times that of the general population, while disease duration of more than 20 years is associated with a cancer risk 32 times greater than that of the general population. The extent of colonic involvement in colitis also influences the risk of cancer. The incidence of cancer when ulcerative colitis is limited to the rectum or to the left side of the colon is much lower than when ulcerative colitis involves the entire colon. The colonic malignancy associated with ulcerative colitis is generally an adenocarcinoma evenly scattered throughout the colon. The adenocarcinoma is often flatter than cancers in the general population and has fewer overhanging margins. It is generally considered extremely aggressive.

Answer 133

Answer: D. In the proximal colon bacteria ferments organic carbohydrates to the SCFAs acetate, propionate, and butyrate. These SCFAs augment Na, Cl, and water absorption and are the fuel for colonocytes. They also regulate proliferation, differentiation gene expression, and immune function in the colon. Three types of electrical activity in colonic circular smooth muscle are slow wave, 2 to 4/ min; membranous potential oscillations (MPOs), 18/min; and action potential superimposed on slow waves and MPO. In humans colonic motor activity varies from quiescence to isolated contractions, bursts of contractions, and propagated contractions. Irregular contractions are predominant. Propagated contractions are low (5-40 mm Hg) and high (75 mm Hg). High propagated contractions occur 6 times/ day originating in the cecum, are responsible for mass movement, and occur more while awake and after meals

Answer 134

Answer: E. Colonic adenocarcinoma is the primary cause of death in patients with FAP. If colectomy is not performed, 100% of these patients will progress to cancer of the colon. The second most common cause of death is duodenal adenocarcinoma. These patients develop periampullary and duodenal adenomatous polyps, which present 10 to 15 years after the colonic polyps and will also progress to adenocarcinoma. Surveillance endoscopy is required every 1 to 3 years to excise or fulgurate these polyps. The third most common cause of death in FAP patients is development of desmoid tumors, which can locally expand and involve mesenteric, vascular, or urologic structures, making surgery difficult or impossible

Answer 135

Answer: C. Ileocecal Crohn disease represents the most common site of presentation, occurring in -40% to 50% of patients. This is followed by colonic disease (which can occur in any segment of the colon) in -30% of patients. Crohn disease isolated to the small bowel (not including the terminal ileum) occurs in approximately another 30%. Oral, gastric, and duodenal diseases are thought to be histologically present in 20% to 40% of patients, but are only symptomatic in about 4%. Perianal involvement occurs in -15% of patients and presents as abscesses and fistulas.

Answer 136

Answer: D. Studies have shown that the extent of mural spread from colon cancer is approximately 2 cm. These findings have led to the convention that 5 cm are appropriate proximal and distal margins for colon cancer resection. In patients with mid-to-low rectal cancers, a 2-cm distal margin is considered acceptable if it results in sphincter preservation. High ligation of the main feeding vascular pedicle and mesentery is done because this is the drainage pattern for venous and lymphatic flow from the tumor. Negative radial margins are required to prevent local recurrence of cancer. This means that involved structures should be resected en bloc if possible. Twelve lymph nodes within a specimen are considered the appropriate number to allow adequate pathologic staging of a tumor. Sentinel lymph node assessment and/or biopsy in colorectal cancer has not been adopted as the standard of care.

Answer 137

Answer: C. Screening and surveillance for colorectal cancer are based on a patient's risk factors. A personal history of adenomas or colorectal cancer, a family history of adenomas or colorectal cancer in I first-degree relative or 2 second-degree relatives, hereditary colon cancer syndromes, or IBD places a person at increased risk. Age by itself and diverticulitis do not increase the risk of colorectal cancer above that of the average population. Actual screening and surveillance recommendations vary by organization and have been put forth by the U.S. Preventive Services Task Force, the NCCN, and the American College ofGastroenterology, among others.

Answer 138

Answer: D. Pseudomembranous plaques are the classic colonoscopic findings in C. difficile colitis, although inflammation or even normal mucosa can be seen. Patients may present with a variety of clinical signs and symptoms, including but not limited to abdominal pain, diarrhea, or sepsis after even a single dose of antibiotics, and a high clinical suspicion is necessary. Clindamycin and cephalosporins are common culprits. Treatment options include IV and oral metronidazole, oral vancomycin, and vancomycin enemas. Gels and foams are not sufficient for hand cleansing after coming in contact with C. difficile spores. Washing the hands with soap and water for at least 60 seconds is necessary, and rooms and objects must be disinfected with bleach.

Answer 139

Answer: D. This patient has a distal obstructing rectal tumor and needs surgery to relieve his obstruction. A stent would not work due to the close proximity to the patient's anus. A loop ileostomy would be incorrect because it would create a closed loop obstruction as long as his ileocecal valve is competent.

Answer 140

Answer: D. The patient has ulcerative colitis and is now found to have dysplasia on colonoscopy. This is an indication for operative management. In an elective setting it is possible to create a restorative proctocolectomy with a Jpouch anastomosis. In an emergent setting, a total abdominal colectomy with end ileostomy would be an appropriate option. It is not appropriate to perform a segmental resection due to the increased risk for colon cancer in patients with ulcerative colitis.

Answer 141

Answer: C. The best imaging modality for rectal cancer has now become MRI. This allows to evaluate for depth of invasion, proximity to the sphincter muscles, and if there are any abnormal lymph nodes in the mesorectal fat.

Answer 142

Answer: C. This patient was found to have adenocarcinoma of the appendix, which will require a formal resection. Carcinoid tumor of the appendix is the only mass that does not require further resection if it is less than 2 cm and is far from the base of the appendix. A right hemicolectomy is recommended for any noncarcinoid tumor greater than 1 cm.

Answer 143

Answer: D. The description of this patient's presentation and imaging findings suggest a cecal volvulus. There have been limited reports of detorsion with a colonoscope, and the majority of these patients require a right hemicolectomy. This condition occurs due to a lack of retroperitoneal attachments. If there is gangrenous bowel at the time of operation, an end ileostomy can be created. Cecopexy, or fixation of the cecum, is oflimited benefit due to a high recurrence rate.

Answer 144

The workup of this patient has revealed probable lower gastrointestinal (GI) bleeding given the negative nasogastric lavage and the presence of blood throughout the colon on colonoscopy. The source of this bleed, however, has not yet been localized. Fifteen percent of cases of upper GI bleeding may present as lower GI bleeding because of rapid transit through the GI tract. As is often the case with GI bleeding, this patient has a very high perioperative risk for an acute coronary event and even death. A tagged RBC scan is often helpful in localizing the region of slower or recurrent bleeding, but it is not therapeutic for an unstable patient who continues to bleed. Suppression of gastric acid secretion with an H2 blocker or a proton pump inhibitor (PPI) is not indicated in this setting. Mesenteric angiography would be the next step in managing this patient since it can be both diagnostic and therapeutic. Mesenteric angiography can pinpoint the site of active bleeding that may be treated with superselective embolization. Although a concern in the past, the risk of intestinal ischemia is low with this approach. Whenever possible, the site or at least the region of intestinal bleeding should be identified prior to surgery. Laparoscopy is not useful in identifying the source of bleeding. Emergency total abdominal colectomy is rarely necessary and should be a last resort since it is associated with significant morbidity and mortality in elderly and vasculopathic patients

Answer 145

ANSWER: C COMMENTS: A thorough understanding of anatomy is integral to the surgical management of problems of the colon and rectum. The colon has two muscle layers: an outer longitudinal layer and an inner circular layer. The inner layer completely encircles the colon. The outer layer, unlike in the small intestine, is in the form of three grossly recognizable longitudinal strips, or taeniae coli, that do not cover the full circumference of the colon. At the rectosigmoid junction, the three taeniae coli spread out and fuse together to cover the rectum with a longitudinal coat. This explains why acquired diverticula do not form in the rectum. The plicae semilunares are spaced, transverse, crescentic folds that separate the tissue between the taeniae coli and form haustra. They produce a characteristic, intermittently bulging pattern that radiologically permits differentiation of the colon from the small intestine, which has circular mucosal folds known as plicae circulares or valvulae conniventes. In contrast to the plicae semilunares, the plicae circulares go all the way around the small bowel lumen, thereby facilitating radiographic distinction. Usually, the ascending and descending portions of the colon are fused to the retroperitoneum, whereas the transverse and sigmoid portions are free. However, developmental anomalies of fixation, as seen with malrotation and in some cases of volvulus, are not uncommon. Cecal volvulus, for example, could not occur unless incomplete fixation to the retroperitoneum makes it possible for a mobile cecum to rotate around a narrow mesenteric pedicle. Surgeons have traditionally placed the upper border of the rectum at the peritoneal reflection, but this is an external and unreliable landmark. Indeed, the peritoneum may only cover the upper anterior portion of the rectum or may go all the way down to the pelvic floor, creating a deep cu-de-sac. A better definition is the point at which the taeniae have completely merged. The rectum therefore lacks taeniae and appendices epiploicae. This is generally easy to recognize intraoperatively. Posteriorly, the upper rectal mesentery may be narrow since it is a continuation of the sigmoid mesentery and derived from the inferior mesenteric vessels. The rectal mesentery spreads out laterally as it descends and then narrows and thins out as it reaches the anorectal ring. All of this must be removed when operating for middle and lower rectal cancers, the so-called total mesorectal excision (TME).

Answer 146

ANSWER: E COMMENTS: Currently, there is no cure for Crohn’s disease. It is felt to be a systemic autoimmune disease. There is early evidence of genetic predisposition and a weak inheritance pattern, but this seems to require an additional push for the patient to develop the clinical picture of Crohn’s disease (the two-hit theory). This push might be an infection or exposure to an allergen to which the immune system responds. Normally, the immune response will decrease after the inciting event passes and will return to homeostasis. In Crohn’s disease, this ability to downregulate seems to be abnormal and inadequate, leading to persistent inflammation. Medical therapy for Crohn’s disease is aimed at general or targeted control of the immune system and inflammation. Most medications such as steroids and many of the older immunosuppressants like azathioprine, 6-mercaptopurine, and methotrexate have broad effects on the immune system and many have deleterious side effects, such as increased risk of infections. Steroids such as prednisone are well known for their very high complication rates when used for the long term, even in the young. These include osteoporosis; aseptic joint necrosis; adrenal insufficiency; GI, hepatic, and ophthalmologic effects (glaucoma); hyperlipidemia; growth suppression; central obesity and peripheral wasting; striae; poor healing; Cushingoid facies; buffalo hump; amenorrhea; irritability and wide mood swings; acne; and possible congenital malformations. Sulfasalazine is commonly used for Crohn’s disease. Its active component is 5-aminosalicylic acid (5-ASA). It has been shown to be beneficial in patients with colitis and ileocolitis, but its effectiveness for Crohn’s disease limited to the small bowel is controversial. Sulfasalazine alone has not been proved to maintain remission. Many patients are allergic to the sulfa component of this medication, and so it is not used as much today because of newer options. Mesalamine is a newer drug that also releases 5-ASA. It is available in several oral forms as well as a suppository. Mesalamine is considered a first-line therapy for Crohn’s disease and is also often used in combination with a corticosteroid. Corticosteroids, such as prednisone and budesonide, are very useful in the induction of remission of active Crohn’s disease. Corticosteroids alone are ineffective in maintaining remission and should not be used for longer t han 6 months, if at all possible. Tapering of steroids and transition to other maintenance medications is part of the standard approach to therapy. Antibiotics have been used as adjuncts to other medications. Metronidazole is the most commonly used antibiotic for Crohn’s disease in the setting of perianal disease, enterocutaneous fistulas, or active colonic disease. It seems to have both antimicrobial and immunologic effects, although the mechanism is unclear. Several newer medications have been developed over the last decade, which have had major effects on treatment paradigms. Most of these medications target specific points in the immune inflammatory cascade. These are anti–tumor necrosis factor-α (anti-TNF-α) antibodies that block the TNF-α receptor, which in turn decreases inflammation. It is used to reduce the signs and symptoms of inflammatory bowel disease (IBD) and maintain remission. Infliximab (Remicade) was the first in this class. It has proved to be very useful in treating patients with Crohn’s disease and has some effect on related fistulas. Other options now include adalimumab (Humira), certolizumab pegol (Cimzia), and vedolizumab (Entyvio). Although initially not used as a first-line therapy for Crohn’s disease, these targeting medications are now being added earlier and earlier because of superior response and possible maintenance of remission. Yet, even these medications have potentially serious consequences including the development of lymphoma and infections. Although much discussed, the risk of lymphoma is actually quite low. Attempts to estimate the actual incidence is confounded by the concomitant use of other immune modulators and reliance on retrospective and limited data. Surgical therapy is reserved for consequences of the disease that cannot be well managed medically or to reduce the need for high-risk medications, particularly steroids. Typical surgical indications include fibrotic obstruction, abscesses, perforation, fistulas, anorectal disease, cancer, and the rare instance of life-threatening bleeding. Even with high-quality medical management, 50% of patients with Crohn’s disease will require an operation at some time in their life, and many will need more than one. Most medications have not yet proven to be particularly effective for maintaining remission after surgery.

Answer 147

ANSWER: D COMMENTS: The colon plays an important role in the digestive process for fluids and electrolytes. In healthy subjects, the colon normally absorbs 1 to 2 L of water and up to 200 mEq of sodium and chloride per day. This absorptive capacity can increase up to 5 to 6 L/day, thereby protecting against severe diarrhea and dehydration. The cecum and right colon absorb sodium and water the most rapidly, whereas the rectum is impermeable to sodium and water. Sodium is actively absorbed against chemical and electrical gradients in the colon. Butyrate plays a role in stimulating sodium absorption in the colon. Potassium and chloride are secreted by the colon through sodium-potassium adenosine triphosphatase (Na+, K+-ATPase) and sodium/potassium/chloride (Na+/K+/Cl−) cotransporters. Chloride ions are actively absorbed at the expense of bicarbonate, which is secreted in exchange. The absence of luminal chloride inhibits secretion of bicarbonate. The main anions in stool include the short-chain fatty acids butyrate, acetate, and propionate. The host and the colonic bacterial flora have a symbiotic relationship: the host promotes bacterial proliferation with energy substrates from the diet and cellular debris, whereas bacteria provide the host with butyrate, a bacterial fermentation product and short-chain fatty acid that fuels colonic epithelial cells. Nonstarch polysaccharides, or dietary fiber such as lignin, cellulose, and fruit pectins, are the main substrates for bacterial fermentation. Fermentation takes place mostly in the right colon, with the cecum being the colonic segment where bacteria are the most metabolically active. Colonic transit time and bulking of stool are dependent on the fermentability of nonstarch polysaccharides. The transit time of stool through the colon is also dependent on stool pH, the autonomic nervous system, and the gastrocolic reflex (postprandial increase in electrical activity and colonic tone).

Answer 148

ANSWER: D COMMENTS: This patient should be evaluated for Hirschsprung’s disease. Megacolon may be congenital or acquired. Both forms are characterized by dilation, elongation, and hypertrophy of the colon proximal to a segment of nonperistaltic collapsed bowel causing obstruction. Both are associated with an increased risk for volvulus. Infection with Trypanosoma cruzi (Chagas disease), Hirschsprung’s disease, and neuronal intestinal dysplasia should all be considered in a patient with slow transit constipation and megacolon. Hirschsprung’s disease is caused by congenital absence of ganglion cells in the myenteric plexus of the bowel, which results in the loss of peristaltic activity in that segment of the intestine. The rectosigmoid region is most frequently involved, with the variable extension of the disease proximally. There is a transition zone from normal bowel, which is dilated, to abnormal bowel, which is aganglionic, aperistaltic, and of normal or decreased caliber. Although Hirschsprung’s disease is primarily a disease of infants and children, occasionally patients with Hirschsprung’s disease will present later in life if an ultrashort distal rectal segment is involved. In these cases, patients usually relate a history of constipation dating back to infancy. In most cases, the diagnosis is apparent during the first 24 h of life when the infant fails to pass meconium. A rectal biopsy is diagnostic. In adolescents and young adults, Hirschsprung’s disease can be diagnosed by anal manometry. If the disease is present, the rectoanal inhibitory reflex (relaxation of the internal sphincter in response to rectal distention) is lost because of the absence of normal ganglion cells, necessary for this myenteric reflex. Treatment of Hirschsprung’s disease is surgical. The effected segment plus any markedly dilated bowel above it is resected, and a coloanal anastomosis is constructed. Acquired megacolon may be seen in patients with protozoal colon infections with T. cruzi, which is endemic in South and Central America. This condition has not been reported in North America. T. cruzi causes widespread destruction of the intramural nervous system. Acquired megacolon may also occur in patients with colonic dilation due to chronic constipation because of the loss of voluntary defecatory muscles (e.g., in paraplegia), extreme inactivity (e.g., in poliomyelitis), or voluntary inhibition of defecation (e.g., in psychotic disorders). Resection of the excessive redundant colon is occasionally justified in the latter group of patients.

Answer 149

ANSWER: C COMMENTS: A villous adenoma with the dimensions given has a 30%–50% chance of harboring cancer. An endoscopic biopsy represents a very limited sample size and is not an adequate proof of the lesion’s precise histologic characteristics. In this instance, the finding of dysplasia suggests a high probability of cancer elsewhere in the adenoma. A complete, full-thickness transanal excision of the lesion should be performed so that if a carcinoma is present, its depth of penetration can be assessed accurately. If there is no invasive cancer, the patient is monitored by interval endoscopic examinations because the risk for recurrence is approximately 10%, even though the initial lesion was benign. If invasive cancer is found, the need for further treatment is determined on the basis of the depth of penetration. A T1 cancer is adequately treated by transanal excision, provided that the tumor s not poorly differentiated and lacks vascular or lymphatic invasion and the margins of excision are clear. T2 or T3 cancers should be treated by radical resection because of the much higher rate of lymphatic spread. Radiation therapy is not used for benign lesions and is not necessary for T1 lesions. Some patients may refuse radical resection for a T2 or T3 lesion; radiation with or without chemotherapy may be offered, but this is not the standard of care. Fulguration of these lesions can be performed in very poor-risk patients in whom precise histologic staging is not essential. However, this is not the standard of care for good-risk patients. If there is a local recurrence after the transanal excision of a benign lesion, reexcision, endoscopic fulguration, or argon plasma coagulation may be considered. APR is rarely indicated for benign polyps because many less radical treatment options are now available. Intracavitary radiotherapy was performed for superficially invading malignant lesions earlier, but the unit has not been made for many decades now and so is rarely available. Lesions extending above 6 to 8 cm from the anal verge are best excised with either transanal endoscopic microsurgery (TEM) or transanal minimally invasive surgery (TAMIS). TEM excision has been shown to be much more precise and reliable than transanal excision with standard operating anoscopes. Long-term data on TAMIS is not yet available.

Answer 150

ANSWER: E COMMENTS: APR of the sigmoid, rectum, and anus with a permanent colostomy was originally described by William Ernest Miles in his landmark paper from 1908. It is frequently performed for cancers of the distal part of the rectum and for recurrent or persistent anal cancer. Miles showed that there are three routes of lymphatic spread from rectal cancer: superiorly along the inferior mesenteric artery (IMA) chain, laterally along the middle rectal vessels to the pelvic and iliac chains, and inferiorly along the pudendal and inguinal pathways. At that time, most cancers presented in advanced stages. Subsequently, it has been found that virtually all spread of rectal adenocarcinoma is through the superior route. Spread in the other two directions only occurs when the superior route is obstructed by advanced disease. The APR is a large operation and is associated with many complications such as sexual and urinary dysfunction and poor healing of the perineal wound, especially after radiation. Most benign lesions of the rectum including large and even circumferential rectal adenomas may be removed with a variety of transanal techniques that preserve the sphincter muscles and fecal continence. Curative resection of cancers in the mid and even distal portions of the rectum in some patients can be performed by LAR and either colorectal or coloanal anastomosis without the need for a permanent colostomy. Many studies from the 1940s to the 1960s showed that cure rates were equivalent when comparing APR with LAR as long as margins were not compromised and a complete mesenteric resection was performed. Limiting factors include the need for a distal mural margin of 2 cm, adequate mesorectal excision, and good sphincter function. The end-to-end surgical stapling devices introduced through the rectum have greatly facilitated anastomoses deep in the pelvis. Concerns that local recurrence rates would be higher as a result have not been borne out. Recurrence rates after stapled and hand-sewn anastomoses are the same. APR is usually performed with curative intent, although it may be justified for symptomatic patients (palliative) with a minimal metastatic disease who are expected to survive 6 months or longer. A cancer that produces anal pain and tenesmus usually involves the sphincter muscle or is obstructing. Recurrent cancer following low resection of a distal cancer usually mandates APR. Fecal incontinence if already present will probably worsen following LAR and a deep pelvic anastomosis because of the loss of normal rectal compliance and capacity.

Answer 151

ANSWER: C COMMENTS: Ulcerative colitis is usually limited to the mucosal and submucosal layers of the colon and rectum. The rectum is almost always involved with continuous spread proximally to varying lengths of the colon. The entire colon is involved in at least one-half of patients. The characteristic pathologic finding is crypt abscesses and not noncaseating granulations that are seen in about one-third of patients with Crohn’s disease. Crypt abscesses are disruptions of the epithelium and lamina propria at the base of the colonic crypts of Lieberkühn. They are characterized by sloughing epithelial cells and infiltration of neutrophils and eosinophils in the epithelium and lamina propria. Crypt abscesses are always present with ulcerative colitis but may also be seen with other inflammatory conditions of the colon such as radiation colitis and certain infections. Therefore they are not pathognomonic for ulcerative colitis. An additional common pathologic finding is goblet cell depletion, as opposed to Crohn’s disease, in which the goblet cells are preserved. Ulcerative colitis is most commonly chronic and relapsing in character, although in 10%–15% of patients the disease runs an acute and fulminant course that may present as toxic colitis. Cancers associated with ulcerative colitis are often advanced when diagnosed because the signs and symptoms may be confused with an inflammatory relapse. For this reason, these cancers are associated with a poorer prognosis. Studies have shown that contrary to what was previously believed, cancers in colitis patients do not behave more aggressively than sporadic cancers when similar stages are compared. Cancers associated with ulcerative colitis are more evenly distributed throughout the colon than sporadic cancers that are more common in the rectum and sigmoid, have a higher incidence of proximal involvement, and are frequently multiple.

Answer 152

ANSWER B COMMENTS: Cancer develops in approximately 5%–6% of patients with ulcerative colitis. Patients with pancolitis or disease of long-standing duration (> 8 to 10 years) are at the highest risk. Sigmoid colectomy is not a reasonable option since the finding of high-grade dysplasia is indicative of a high risk for cancer anywhere in the colon, not just where the biopsy was taken. Abdominal colectomy with IRA does not eradicate the disease or remove all of the mucosa at risk for malignant transformation. IRA is now rarely performed for ulcerative colitis because of the presence of persistent disease in the rectum, the risk of neoplasia in the rectum, and poor function because of poor rectal compliance and tenesmus. Historically, the risk for subsequent rectal cancer after an IRA is approximately 20% after 25 years, even with close surveillance. Therefore over 50% of patients will require completion proctectomy because of cancer, dysplastic changes, refractory proctitis, or poor function. Total proctocolectomy with permanent end ileostomy (TPC) is an acceptable operation, particularly when a one-step approach is preferred or when the patient is a poor candidate for a sphincterpreserving procedure because of age, c-morbidities, or poor sphincter function. Healthy, motivated patients who require surgery for ulcerative colitis generally prefer a proctocolectomy with sphincter preservation and IPAA. The continent ileostomy procedure (Kock pouch) with the creation of an internal distal ileal reservoir and an invaginated nipple valve was described in the late 1960s for urinary diversion and then adapted as an alternative for the standard end ileostomy. The pouch must be intubated with a rigid plastic tube multiple times ea ch day to stent the valve open and allow the pouch to empty. Even in the best of hands, these require revision surgery in 25%–30% of patients because of slippage of the nipple valve and incontinence or obstruction. This procedure has been largely replaced by the IPAA operation. The combination of proctocolectomy, an ileal reservoir (J pouch), and IPAA offers advantages over proctocolectomy and permanent ileostomy because not only is the diseased mucosa eliminated but so is the need for a permanent abdominal stoma. The straight ileoanal operation was originally described by Mark Ravich, M.D., and David Sabiston, M.D., in 1947 but was not pursued because of copious diarrhea and frequency. The technique has undergone many modifications, most notably the addition of an ileal pouch proximal to the IPAA. The pouch may be S or J shaped, which increases stool storage capacity and decreases frequency. A temporary diverting ileostomy is usually required for 2 to 3 months while the pouch heals. The procedure is currently recommended for the majority of patients with ulcerative colitis and for patients with familial polyposis. It is not indicated for Crohn’s disease because of the high risk for recurrence within the pouch that may lead to complex fistulas and septic complications. Although advanced age is not an absolute contraindication, elderly patients with multiple comorbid conditions may be better served by a TPC with a permanent ileostomy. For appropriately selected patients, the functional results are good, with preservation of the autonomic innervation to the bladder and genitalia. Fecal sensation and continence are retained in most patients. Daytime incontinence occurs in about 5% and nocturnal incontinence or soiling occurs in 20% of patients. Over 95% of patients retain the pouch over the long term.

Answer 153

Answer: C COMMENTS: Enteric fistulas occur in about 5% of acute cases of colonic diverticulitis. Fistulas usually develop as a consequence of localized abscess formation with perforation into an adjacent hollow organ, typically the bladder, uterus, vagina (after hysterectomy), or small bowel. Most spontaneous diverticular complications occur with the first episode of diverticulitis. Colocutaneous fistulas rarely form spontaneously. They are most commonly seen as a postoperative complication in which they drain through operative incisions or drain tracts. Colovesical fistulas are most frequently the result of diverticular disease, followed in frequency by cancer, Crohn’s disease, radiation-induced colitis, and foreign bodies. The primary symptoms of fecaluria and pneumaturia are associated with the urinary tract. The patient may relate a history of abdominal pain and fever before the development of the fistula. Although a barium enema may give information regarding the site and extent of involvement of the colon with diverticulosis, the fistula is demonstrated in only one-half of the cases. Cystoscopy is often very useful and may demonstrate the fistula opening into the bladder with stool, gas, or mucous passage or erythema and edema of the wall of the bladder, a finding consistent with a fistula. Computed tomography (CT) may reveal a constellation of findings, including air in the bladder, a thickened loop of bowel lying against the bladder, and enteric contrast in the bladder (before intravenous contrast material has been administered). CT has become the diagnostic test of choice. Coloenteric fistulas may cause no symptoms or may produce diarrhea, depending on which segments of bowel are involved with the fistula. Most stable fistulas can be corrected with a one-stage operation, which is the preferred treatment. If bowel preparation is inadequate or there is extensive local inflammation or abscess formation beyond the immediate vicinity of the colon or its mesentery, a staged approach may be required. The first stage includes a Hartmann’s resection of the involved bowel with a colostomy and distal closure along with repair of the bladder. The second stage involves colostomy take down and colorectal anastomosis.

Answer 154

ANSWER: C COMMENTS: The Dukes classification (1932) was the original standardized method for staging CRC. In subsequent years, however, confusion arose because of numerous modifications. The American Joint Committee on Cancer (AJCC) standardized the tumor-nodes-metastasis (TNM) classification that is now used globally (Table 23A.1). The TNM classification stages a tumor according to the depth of tumor invasion into the bowel wall (T), the presence or absence of lymph node involvement (N), and distant metastases (M). A T1 tumor penetrates only into the submucosa, whereas a T2 tumor partially invades the muscularis propria. Transmural penetration imparts a T3 designation, a T4a lesion comes through to the serosal surface of the bowel, and a T4b tumor invades into an adjacent structure. An N0 lesion has not metastasized to regional nodes, an N1 lesion involves three or fewer lymph nodes, and an N2 lesion has metastasized to four or more lymph nodes. The designations M0 and M1 indicate whether there are distant metastases. It is recommended that a minimum of 12 lymph nodes should be examined for reliable nodal staging. Stage I is T1 or T2 only, stage II is T3 or T4 only, stage III is any lymph node involvement (or tumor deposits separate from the primary), and stage IV is any distant metastases (Table 23A.1). Prognosis is clearly differentiated by these stages, and survival has gradually improved over time with better surgery and better adjuvant therapy. Stage I colon cancer patients have a 5-year disease-free survival (DFS) rate of about 90%. Stage II patients who have had appropriate surgical resection have a 5-year DFS of about 75%. Stage III cancer patients treated by surgery alone have a 5-year survival of about 30%, but with adjuvant therapy the 5-year survival will rise to 60%–70%. Stage IV colon cancer carries a poor prognosis, with a 5-year survival rate of 5%. Some patients with disease limited to the liver or the lungs may be treated for cure.

Answer 155

ANSWER: C COMMENTS: True diverticula contain all layers of the bowel wall and are generally congenital. False diverticula lack the muscularis propria and are acquired. Sigmoid diverticula are acquired false diverticula. Isolated cecal diverticula are usually true or congenital. However, acquired diverticulosis may affect all parts of the colon (pandiverticulosis). Cecal diverticulitis is relatively uncommon, and 80% of cases are initially diagnosed as acute appendicitis or, occasionally, perforated cancer. It is more common in patients of Asian descent. In patients with repeated attacks, the cecal inflammation and subsequent fibrotic scarring may be indistinguishable from cancer. Such an inflammatory mass of the sigmoid colon may resemble a cancer at laparotomy. Treatment depends on symptoms, complications, and the number and severity of recurrent episodes. Incidentally found asymptomatic diverticula do not require surgery. Surgical options depend on the extent of inflammation. If the inflammation is minimal and limited, segmental resection and anastomosis may be performed. If there has been perforation with frank feculent peritonitis, a Hartmann’s resection with a proximal ostomy and distal closure is performed. A middle of the road option is resection with anastomosis and proximal diverting loop ileostomy. Closure of the loop ileostomy is a much smaller operation than closure after a Hartmann’s procedure.

Answer 156

ANSWER: B COMMENTS: This patient’s presentation is most consistent with ulcerative colitis. In ulcerative colitis, the anus is spared, whereas in Crohn’s disease, the anal or perianal disease is the first manifestation in up to 25% of patients. The anal disease ultimately develops in 50%–70% of patients with Crohn’s colitis. Rectal involvement can be seen with both of these inflammatory diseases of the colon but is more common in ulcerative colitis (95% vs. 50%). The small bowel is extensively involved in approximately 50% of patients with Crohn’s disease, whereas “backwash ileitis,” a nonspecific dilation of the terminal ileum, occurs in about 10% of patients with ulcerative colitis and has no prognostic or physiologic implications. The clinical features of these two entities are similar: chronic diarrhea, cramping, abdominal pain, and fever. Bloody stools are quite common with ulcerative colitis and are much less frequent with Crohn’s disease. Removing the entire colon and rectum is curative in ulcerative colitis, whereas there is no curative operation for Crohn’s disease since it may involve any part of the intestinal tract. Total proctocolectomy for isolated colonic involvement of Crohn’s disease has the lowest recurrence rate of any operation for that disease, yet recurrence in the small bowel is still seen in more than 25% of patients. Moreover, one-third of patients require additional surgery for such recurrence. Toxic megacolon can be an emergency, life-threatening complication of either ulcerative colitis or Crohn’s disease, although it is more common in ulcerative colitis. Surgery for ulcerative colitis has two goals: eliminate the disease and provide reasonable GI function. Common surgical options today are total proctocolectomy with end ileostomy or proctocolectomy with sphincter preservation and IPAA. Yet, even when clinical and pathological findings confirm ulcerative colitis, recurrence or development of Crohn’s disease in the small bowel and especially in the pouch or anus occurs in about 5% of patients after proctocolectomy.

Answer 157

ANSWER: D COMMENTS: In the United States, CRC is second only to lung cancer as the leading cause of death from cancer when both genders are considered. Environmental factors, particularly dietary habits, may explain the wide variation in the geographic distribution of colon cancer. This patient has familial polyposis. Genetic factors play a definite role in carcinogenesis, and mutational abnormalities have been identified in patients with familial polyposis and hereditary nonpolyposis colorectal cancer (HNPCC) syndromes. Cancer develops in almost 100% of patients with familial polyposis, usually by the age of 40 years, if the colon is left untreated. In HNPCC syndrome, the lifetime risk for the development of colorectal cancer approaches 80%. Diets low in fiber and high in animal fats and protein are associated with an increased risk for colon cancer. The mechanisms may include alterations in intestinal transit time and an increase in the formation of carcinogenic compounds as a result of bacterial metabolism of dietary components. Gallstone disease appears to be more common in areas where colon cancer is prevalent. Some studies have suggested that cholecystectomy is associated with a higher incidence of subsequent colon cancer, particularly that involving the right colon. A proposed mechanism for this relationship is related to the carcinogenic potential of secondary bile acids, to which the intestinal mucosa is increasingly exposed after cholecystectomy as a result of increased enterohepatic cycling. However, evidence supporting this association is conflicting, and any association that may exist is minimal. Risk factors for the development of cancer in patients with ulcerative colitis include disease of long duration (the incidence increases by 1%–2% per year after 10 years) and total colonic involvement. An increased risk for cancer has also been seen in patients with Crohn’s disease of both the small and large intestines, particularly in bypassed segments. The aforementioned notwith- standing, familial polyposis, HNPCC syndrome, and ulcerative colitis account for only a small percentage of the total cases of CRC; most colon cancers occur sporadically without a genetic or inflammatory predisposition.

Answer 158

ANSWER: A COMMENTS: Actinomycosis is a suppurative, granulomatous disease caused by Actinomyces israelii, an anaerobic, gram-posi- tive bacterium that produces chronic inflammatory induration and sinus formation. Although the causative organism is often part of the normal oral flora, infections may occur in the cervicofacial area, thorax, or abdomen. The cecal region is the most frequent site of abdominal infection. A pericecal mass, abscesses, and sinus tracts may be seen. Rectal strictures have been reported as well. Treatment consists of surgical drainage and penicillin or tetracycline. Lymphogranuloma venereum is a sexually transmissible disease caused by Chlamydia trachomatis. It occurs most frequently in men who have sex with men. It starts as proctitis with symptoms of tenesmus, discharge, and bleeding. Perianal and rectovaginal fistulas and rectal strictures may develop. The diagnosis is made with the Frei intracutaneous test when it is available. Otherwise, the diagnosis may be confirmed by a complement fixation test. Tetracycline is curative, and steroids are occasionally recommended. Tuberculous enteritis is seen most commonly in the ileocecal region and occasionally leads to stenosis of the distal ileum, cecum, and ascending colon; the endoscopic and radiographic features produced may be indistinguishable from those of Crohn’s disease. Surgery is reserved for patients with obstruction. A triple-drug therapy consisting of isoniazid, p-aminosalicylic acid, and streptomycin usually heals the intestinal lesions. Yersinia infections are caused by a gram-negative rod that is transmitted through food contaminated by feces or urine. It is often associated with eating undercooked pork. It produces a clinical picture frequently indistinguishable from that of acute appendicitis with fever and right lower quadrant abdominal pain. Yersinia may also cause acute diarrheal gastroenteritis. It primarily affects the ileocecal region. Diagnosis is made by stool cultures or a poly- merase chain reaction (PCR) probe. Scanning often shows inflam- mation and thickening of the terminal ileum. Yersinia enterocolitis may be self-limited. When suspected or diagnosed, it generally responds promptly to treatment with tetracycline, streptomycin, ampicillin, or kanamycin. Amebic colitis is caused by the protozoan E. histolytica. It primarily affects the colon and rectum and may secondarily infect other organs such as the liver. Up to 10% of the American population are asymptomatic carriers. Transmission of the disease is through food or water contaminated with feces containing Ent amoeba cysts. The disease can assume an acute or a chronic form. Treatment is metronidazole, 750 mg three times a day for 10 days.

Answer 159

ANSWER: A COMMENTS: CRC is the leading cause of colon obstruction in industrialized countries, and left-sided tumors in particular are susceptible to obstruction because of the more formed con- sistency of the stool. This scenario may also be seen with other types of primary or metastatic cancer, diverticular disease, and radiation- or ischemia-induced stricturing. For left-sided tumors producing obstruction, the traditional surgical approach was an initial decompressive transverse colostomy, followed by resection within 7 to 10 days, and often a third-stage operation for the closure of colostomy. Initial treatment by decompressive colostomy alone is still appropriate for poor-risk or debilitated patients and for those with a marked colon dilation. The most common approach today is the Hartmann’s procedure—primary resection of the obstructing pathologic entity, colostomy, and distal closure. The distal side may also be brought out as another ostomy (mucous fistula) for decompression, to provide a route for distal washout, and when the viability of the end may be in question. The colostomy (and mucous fistula, when present) is taken down, and an anastomosis is constructed at a second stage. Some surgeons advocate primary subtotal or total colectomy with an ileocolic or IRA as a one-stage procedure for left-sided obstruction. However, this may result in diarrhea and incontinence, especially in older patients. Most right and transverse colon cancers with obstruction can be treated safely by primary resection and reanastomosis as a one-stage procedure as long as the ileum is minimally distended and healthy. In the absence of peritonitis or perforation, an alternative approach consists of resection followed by intraoperative colonic irrigation and then primary anastomosis if the proximal bowel is not compromised. Colonic irrigation to wash out the lumen is performed by placing either a cecostomy or an appen- dicostomy tube, mobilizing the proximal colon margin site enough to hang it over the lateral abdominal wall, and creating a controlled conduit for the effluent to exit through a large- caliber anesthesia tubing or a long plastic sleeve fixed in the lumen. Several liters of saline solution are washed through the colon while manually breaking up stool and milking it down the lumen. This process is rather arduous and time consuming. Anastomoses created with this technique have a clinical leak rate of 5%–7% or more. It is not appropriate when the patient is not stable or when the bowel is at all compromised. This technique is not used very often. Endoscopically placed colon stents are now commonly used to decompress patients with both malignant and benign strictures. Stents may be used for palliation of a patient with an extensive metastatic disease or as a bridge to surgery. They cannot be used in low rectal cancers since they protrude for several centimeters below the tumor and may cause considerable pain if ending in the very low in the rectum or anal canal. Stricturoplasty has no role in managing colon obstruction. It is used primarily for patients with benign fibrotic small bowel strictures due to Crohn’s disease.

Answer 160

ANSWER: A COMMENTS: PJS is a disorder characterized by intestinal hamartomatous polyps along with skin and mucosa pigmenta- tion or “cafe-au-lait” spots. It is due to a mutation in the STK11 gene on chromosome 19 and is inherited as an autosomal domi- nant trait. Hamartomas are lesions in which normal tissue is found in an abnormal structural configuration. Hamartomatous polyps are found primarily in the jejunum and ileum, with involvement of the colon and rectum in one-third and the stomach in one-fourth of patients. The polyps may cause obstruction, intussusception, or bleeding. The pigmented spots are found on the oral mucosa, lips, palms of the hands, and soles of the feet. There is an increased incidence of many cancers in PJS, including those in the pancreas, liver, lungs, breast, ovaries, uterus, and testicles. However, the polyps themselves do not become cancerous very often. Gastric and colon polyps are usually treated by polypectomy. Small bowel polyps may be seen on capsule endoscopy. Symptomatic small bowel polyps may be localized with intraoperative total endoscopy, marking of each site, and serial enterotomy with surgical polypectomy when symptomatic. Sporadic juvenile polyps in children are solitary 70% of the time, and in 60% of cases they are located within 10 cm of the anal verge. They are thought to be a developmental abnormality and may bleed or prolapse. The syndrome of juvenile polyposis is characterized by the presence of multiple hamartomatous polyps in the stomach, small bowel, or colon, with large “mucous lakes” on pathology. Mutations in the BMPR1A and SMAD4 are usually found. It has an autosomal dominant inheritance pattern. Signs and symptoms of anemia, anergy, hypoproteinemia, and failure to thrive may be seen. Solitary juvenile polyps seem to have little propensity for malignancy; however, up to 40% of patients with juvenile polyposis will develop a CRC. Cronkhite-Canada syndrome (CCS) is a sporadically occurring polyposis syndrome not thought to be inherited. It is diagnosed mostly in patients of Japanese descent, but it can occur in any ethnic group. The polyps are hamartomas, often have an inflammatory component, and may be anywhere along the GI tract. In addition, there are pigmented skin areas, alopecia, and atrophy of the finger- nails and toenails. The syndrome may be due to an autoimmune disorder since there are elevated levels of immunoglobulin (Ig)G4, and it often responds to treatment with steroids and immunosup- pressives. There seems to be an increased risk of colorectal neoplasia, but because of its rarity, the level of risk is not clear. Nevertheless, regular screening is recommended. Familial adenomatous polyposis (FAP) is the best characterized inherited CRC syndrome and is due to an autosomal dominant mutation in the adenomatous polyposis coli (APC) gene. Patients develop hundreds to thousands of polyps by their early teens. Although most are in the colon, many patients also develop duodenal and jejunal polyps, which can be very difficult to manage. Periampullary cancer is a significant risk. Most patients with FAP do not have extraintestinal manifestations; however, Turcot and Gardner syndromes are variants that do. Patients with Turcot syn- drome develop central nervous system tumors, and patients with Gardner syndrome develop osteomas, exostoses, and desmoid tumors, which may be quite debilitating.

Answer 161

ANSWER: A COMMENTS: Ischemic colitis should be considered in the dif- ferential diagnosis of any elderly patient with lower abdominal pain. It can also be found in individuals of any age in association with hypercoagulable states, periarteritis nodosa, systemic lupus erythematosus, rheumatoid arthritis, polycythemia vera, and sclero- derma. Ischemic colitis may be manifested as three distinct clinical syndromes, depending on (1) the extent and duration of vascular occlusion, (2) the adequacy of the collateral circulation, and (3) the extent of septic complications. Approximately 80% of the blood flow to the wall of the colon reaches the mucosa and submucosa, and the remaining 20% supplies the muscularis. Despite the extensive collateral vessels to the colon, it receives only about 50% of the blood flow that the small intestine does. The colon is therefore more sensitive to ischemic injury during acute reductions in blood flow. In contrast to other areas of the body, an increase in functional motor activity of the colon does not result in a parallel increase in absolute colonic blood flow. Ischemic colitis appears to be a disease of the small arterioles. Although this disease can occur in any segment of the large bowel, it is seen most commonly in the splenic flexure or distal sigmoid colon. A plausible explanation is that these areas may receive sub-optimal blood flow since they are positioned between two vascular systems (“watershed areas”) that rely on an intact but meandering artery for their blood supply. Sudeck’s point is the area between the blood supply from the last sigmoid artery and the superior rectal artery. However, the clinical significance of Sudeck’s point is questionable because of retrograde flow from the middle and inferior rectal arteries. Griffith’s point is the vulnerable area at the splenic flexure that is positioned between areas of the colon perfused by the left branch of the middle colic artery and the ascending branch of the left colic artery. The diagnosis is often made by an endoscopic examination that reveals cyanotic, edematous mucosa that may be covered with exudative membranes. Barium enema may show the typical “thumbprinting” of the edematous bowel wall. Injection angiography or CT angiography may be helpful in the questionable patient. However, if gangrenous colitis is suspected on the basis of ominous physical findings, such as involuntary guarding and rebound tenderness and shock, these studies are con- traindicated and prompt laparotomy is mandatory. Transient ischemic colitis without full-thickness necrosis usually responds to nonoperative management. Parts of the mucosa may slough, but the muscularis remains intact. Late consequences include ischemic strictures that may be resected electively with primary anastomosis after the initial ischemic episode has subsided. If surgery is needed for peritonitis and gangrenous colitis, resection with end colostomy is the preferred operation (Hartmann’s proce- dure or double-barreled colostomy).

Answer 162

ANSWER: A COMMENTS: Although screening recommendations initially involve utilizing stool guaiac and flexible sigmoidoscopy, most patients are still screened by colonoscopy. Determining the initiation and timing of screening colonoscopies requires physicians to take a thorough personal and family history of colorectal and other diseases. Briefly, the timing of screening initiation varies by the patient’s history of IBD or genetic predisposition to the disease and by the family history of disease. The interval is determined by the age of onset of disease in the patient’s family history as a surrogate for the aggressiveness of disease. All recommendations are a guideline and may be adjusted to more frequent intervals if a colonoscopy reveals positive findings. It is important to note that these recommendations exist only for screening colonoscopy; should a patient present with changes in bowel habits, rectal bleeding, or other concerning symptoms, the colonoscopy is considered diagnostic and is obtained immediately without regard to the screening age. The screening recommendations for colonoscopy are as follows: • Patients with no family history of CRC or polyps—begin at age 50 and repeat at 10-year intervals * Patients with a first-degree relative with CRC or polyps at age 60 or older (or two first- or second-degree relatives of any age)—begin at age 40, or 10 years before the earliest diag- nosed age, and repeat at 10-year intervals * Patients with a first-degree relative with CRC or polyps at age 60 or younger (or two first-degree relatives of any age)—begin at age 40, or 10 years before the earliest diagnosed age, and repeat at 5-year intervals * Patients with known HNPCC—begin at age 20 to 25 years and repeat at 1- to 2-year intervals * Patients with a known family history of FAP—begin flexible sigmoidoscopy at puberty and perform annually until 25 or until the colon and rectum are removed. If negative at 25, perform colonoscopy every 10 years * Patients with known ulcerative colitis—begin at 8 to 10 years after the onset of the disease and repeat annually * Patients with known Crohn’s colitis—similar to ulcerative colitis

Answer 163

ANSWER: E COMMENTS: This patient has a carcinoid tumor of the rectum. This is a neuroendocrine tumor. This group of tumors includes a wide and diverse set of neoplasms that range from small, completely benign lesions to large, poorly differentiated cancers with an extremely dismal prognosis. These neoplasms have the potential of storing large amounts of an amine precursor (5-hydroxytrypto- phan), and through the amine precursor uptake and decarboxylation (APUD) system, these lesions may produce several biologically active amines including serotonin. Carcinoids may be found anywhere along the GI tract and in the pulmonary tree and may occasionally be found elsewhere. They are generally divided into foregut, midgut, and hindgut. The most common locations are the appendix and ileum (midgut), rectum and colon (hindgut), and stomach (foregut). Rectal carcinoids are fairly common and account for 12%–15% of lesions, while colon carci- noids are relatively rare and account for only 2.5% of all GI lesions. The incidence of invasive malignancy and metastases to regional lymph nodes correlates well with the size of the carcinoid for both colonic and rectal lesions. Carcinoids larger than 2 cm are malig- nant 90%–95% of the time, while lesions smaller than 2 cm are malignant only 5% of the time. GI carcinoids typically arise in the submucosa. Rectal lesions smaller than 2 cm rarely invade the muscularis or spread to the lymph nodes and very rarely secrete metabolically active sub- stances. Therefore they are not associated with carcinoid syndrome and symptoms of flushing, diarrhea, and heat intolerance. They may be locally excised transanally. Enucleation is not appropriate. Recurrence is rare if margins are clear. Rectal lesions larger than 2 cm or those that have penetrated into the rectal muscularis are usually aggressive neuroendocrine cancers. Metastatic evaluation is necessary. If widespread metastases are not present, these malignancies are best treated by APR and colostomy or LAR with anas- tomosis if higher in the rectum. These tumors are not particularly radiosensitive, and no specific chemotherapy regimens have been shown to be particularly effective. However, large series are lacking because of the relative rarity of these lesions, and radiation and chemotherapy are used selectively for palliation. Malignant colon carcinoids are treated by formal oncologic resection with wide lymphatic clearance. Up to two-thirds of patients with neuroendocrine cancers of the colon are found to have either local spread or systemic metastases at the time of diagnosis. If disseminated disease is present, resection of the primary lesion is still recommended to alleviate symptoms and avoid bleeding and obstruction. Carcinoids of the colon infrequently produce carcinoid syndrome, although occasional lesions that have metastasized to the liver will do so.

Answer 164

ANSWER: A COMMENTS: The most important determinant of the type of operation to perform for a rectal cancer is the location of the lesion within the rectum. Tumors located 0 to 5 cm from the anal verge, especially those that involve the sphincter muscle and are produc- ing pain, are best treated by APR. Approximately 10%–15% of tumors within this region can be considered for local excision if they are minimally invasive (Tis or T1—no deeper than the submucosa), are not poorly differentiated, and do not have a lymphovascular or perineural invasion. A coloanal anastomosis can be performed when the distal margin is 2 cm after mobilization, although functional results are often poor. Lesions in the upper part of the rectum (10 to 15 cm) are amenable to anterior resection, with the restoration of intestinal continuity by colorectal anastomosis. Lesions located in the mid-rectum (5 to 10 cm) are treated by a variety of operations, depending on the skill of the surgeon and the patient’s body habitus. Most cancers in this region can be treated by LAR with colorectal anastomosis or coloanal anastomosis. A temporary loop ileostomy is often used to protect the low colorectal anastomosis, especially in radiated patients because of the higher risk of anastomotic leak. Impaired fecal continence has been noted in 10%–35% of patients after coloanal anastomosis. Part of the degradation in the function is due to the loss of the rectum’s capacity and storage function. Techniques such as the construction of a colonic J pouch or performance of a coloplasty to widen and increase the compliance of the distal colon may improve function but have not been adopted widely. The decision to perform a sphincter-saving operation must be individualized, and safety is a primary concern. If the patient is obese or debilitated; if the pelvis is long, narrow, and angulated; if a satisfactory anastomosis cannot be performed; or if sphincter function is poor, an APR may be the best choice. Low rectal carcinoids larger than 2 cm should be treated with radical resection (APR or LAR) and lymphadenectomy. Smaller lesions may be treated with local excision.

Answer 165

ANSWER: B COMMENTS: The amount of colon resected when operating with the intent to cure colon cancer is based more on the need for removal of the draining mesenteric lymph nodes that parallel the vascular supply to that area of the colon. The IMA arises from the aorta 3 to 4 cm above the aortic bifurcation. The left colic artery splits off about 3 cm below the origin of the IMA and ascends in the mesentery to meet the marginal artery of Drummond that communicates with the left branch of the middle colic artery and the superior mesenteric artery distribution. Below the left colic artery, the IMA gives off several sigmoidal branches and finally terminates as the left and right superior rectal arteries. Sigmoid cancers should be resected with at least a 5-cm margin and usually much more since this is not the determining factor. The need for wide mesenteric clearance is important since up to one-third of patients with involved lymph nodes are cured by proper resection alone. Adequate lymph node clearance also provides a large number of nodes for sampling to determine the stage. At least 12 lymph nodes must be evaluated, but a comprehensive pathologic examination will often identify 30 nodes or more. The more nodes evaluated, the more accurate the staging. High ligation of the IMA at its takeoff from the aorta used to be advocated to get the highest lymph nodes; however, subsequent studies have shown that the division of the IMA just below the left colic artery results in equivalent outcomes and decreases the risk of left colon ischemia. For a sigmoid cancer without the evidence of distal spread, the resection should include the entire sigmoid colon to just above the descending colon–sigmoid junction proximally and to the true rectum where the taeniae coli spread out and become a full longitudinal coat of the rectum distally, plus at least 5 cm on either side of the tumor. If the tumor is at or adjacent to this distal level, a portion of the upper rectum should be removed as well (LAR). It is important to note that the point where the sigmoid becomes the rectum is defined by a complete longitudinal muscle layer and not by any extrinsic landmark such as the sacral promontory or the “peritoneal reflection,” which are meaningless in this context. Resection of the entire intraabdominal colon may be considered for patients with an obstructing cancer because resection of a dilated stool-laden colon may safely permit an ileorectostomy rather than a colostomy. Other indications for a total colectomy include synchronous cancers in separate segments of the colon cancer or in patients with known familial polyposis or Lynch syndrome because of the high risk of metachronous cancers. Oophorectomy may be considered in postmenopausal women because approximately 6% of these patients have simultaneous drop metastases to the ovaries, and it removes the risk of ovarian cancer. Routine prophylactic oophorectomy does not improve survival in general. Isolated recurrence in an ovary is fairly uncommon, and less than 2% of women with CRC subsequently undergo ovarian resection. Additionally, spread to the ovaries is a sign of disseminated disease, and oophorectomy is not associated with increased survival.

Answer 166

ANSWER: B COMMENTS: HNPCC syndrome is categorized into two forms depending on whether it is isolated (Lynch syndrome I—colon cancer alone) or associated with extracolonic tumors (Lynch syndrome II—endometrial, ovarian, breast, urothelial, biliary, and gastric). HNPCC accounts for approximately 5% of all CRCs and is caused by mutations in one of the several mismatch repair genes, allowing the propagation of errors in DNA replication. These genes include MSH2, 60%; MLH1, 30%; MSH6, 7%–10%; and PMS2, <1%. Inheritance is autosomal dominant. Colon cancers are more common on the right colon (72%), are frequently synchronous (more than one at a time—18%), and are frequently metachronous after segmental colectomy (have a second colon cancer develop later—40% in 10 years). Therefore patients undergoing only segmental colectomy have a high rate of developing another colon cancer. In HNPCC, the risk of developing colon cancer is over 80%, endometrial cancer 60%, stomach cancer 15%, ovarian cancer 10%, hepatobiliary cancer 5%, urinary tract cancer 5%, small bowel cancer 3%, and brain cancer 2%. Although patients with HNPCC have a high rate of developing colon cancer, the overall survival is actually better in them than in patients with sporadic cancers. Identifying patients and families with HNPCC requires vigilance but is quite important. The Amsterdam Criteria, developed in 1990, is the original method and uses the 3-2-1 rule: • 3 successive generations affected by CRC, • 2 first-degree relatives affected by CRC, and • 1 affected person younger than 50 years. This was fairly reliable in that people satisfying the criteria were highly likely to have HNPCC. However, there are many patients with HNPCC who do not quite satisfy these criteria, for example, small families with few siblings or cousins or spontaneous mutations. In addition, the presence of extraintestinal cancers was not included. Therefore, in 1998, the revised Amsterdam II Clinical Criteria were released: • 3 or more relatives with an associated cancer (colorectal, endometrial, small intestine, ureter, or renal pelvis), • 2 or more successive generations affected, • 1 or more relatives diagnosed before the age of 50 years, • 1 should be a first-degree relative of the other two, • FAP should be excluded, and • Tumors should be verified by pathologic examination. The Amsterdam Criteria were developed before the genes responsible for HNPCC were known and before genetic testing was available. They are exclusionary with a high degree of specificity but low sensitivity (62%). Now, testing by immunohistochemical staining of tumor specimens and direct genomic characterization is possible and reasonably inexpensive. A new approach was needed. The National Cancer Institute developed the Bethesda Guidelines to identify patients who are candidates for genetic testing. These guidelines are much more inclusive and cast a wide net. Alone they are not terribly specific, but with appropriate testing, they are estimated to be 94% sensitive. The current Revised Bethesda Guidelines from 2004 state that anyone who satisfies any one of the following criteria is a candidate for further testing: • CRC diagnosed in a patient who is less than 50 years old • Presence of synchronous or metachronous CRC or other Lynch syndrome–associated tumors, regardless of age • CRC with high microsatellite instability histology diagnosed in a patient less than 60 years old • CRC diagnosed in one or more first-degree relatives with a Lynch syndrome–associated tumor, with one of the cancers being diagnosed at less than 50 years of age • CRC diagnosed in two or more first-degree or second-degree relatives with Lynch syndrome–associated tumors, regardless of age Family members at risk should undergo biannual colonoscopy beginning at age 25 or 10 years younger than the age of the youngest affected family member. Women should have an annual pelvic examination and pelvic ultrasound to examine the ovaries and the thickness of the endometrial stripe. Serum markers for ovarian cancer should be checked, and mammograms should be obtained earlier than usually advised. Family members of an afflicted individual should be counseled and offered genetic screening. Total colectomy with IRA should be recommended for HNPCC patients with a new colon cancer because of the high risk for metachronous tumors. If a woman has completed childbearing, hysterectomy and bilateral salpingo-oophorectomy should also be recommended at the time of colectomy.

Answer 167

ANSWER: C COMMENTS: Radiation therapy is used in the treatment of cervical, uterine, anal, rectal, and prostate cancer. It is a very effective treatment but may result in severe side effects due to dose-depen- dent cell death in normal surrounding structures. Injury from radiation therapy occurs via damage to DNA and production of oxygen free radicals. The maximum safe therapy is considered to be 6000 to 8000 cGy, depending on the tissue, but side effects can occur at much lower doses. The effects of acute radiation toxicity tend to manifest in the first 6 months as villous atrophy and degeneration of the mucosal lining. At 6 to 12 months following radiation, patients develop a progressive microvascular fibrosis (obliterative arteritis), causing thrombosis and ischemia. Acute radiation proctitis typically manifests as diarrhea, mucous discharge, tenesmus, and bleeding. Chronic changes frequently present as nonhealing ulcerations and telangiectasia fistulas, thickening, and stricture. Symptoms differ between those induced with external beam radiation therapy and those induced with brachytherapy. Most patients can be adequately treated with symptomatic control, antidiarrheals (after infectious causes are ruled out), and hydration. Sulfasalazine and sucralfate enemas can provide relief in some patients. Other modalities to control bleeding may include argon beam plasma (APC) coagulation, hydrocortisone enemas, and topical application of formaldehyde (4%–10%) under direct vision. Although ulcerative colitis and new rectal primaries can present with tenesmus and bleeding, they are unlikely causes of new symptoms in this patient with prior radiation. Ischemic colitis must be ruled out but again is inconsistent with the clinical history. Recurrent cervical cancer is unlikely to cause these symptoms with normal imaging.

Answer 168

ANSWER: B COMMENTS: Creation of an IPAA is associated with low mortal- ity but considerable morbidity. Small bowel obstruction can occur in up to 20% of patients; this high figure is expected given the extent of underlying inflammation as well as the colectomy and extensive mobilization of the small bowel. Pelvic sepsis occurs in up to 5% of patients. It may present early or late, usually manifesting as an abscess or perineal fistula. The main symptoms are anal pain, tenesmus, fevers, and purulent discharge from the anus. The diagnosis is confirmed with CT imaging, which may show a discrete abscess or only soft tissue thickening. Antibiotics should be started immediately, and any fluid collections should be drained percutaneously or unroofed trans- anally if inaccessible. A return to the operating room for laparotomy is rarely necessary. In the literature anastomotic stricture occurrence has been reported in a variable percentage of patients and is best avoided by a tension-free anastomosis and rapid control of any developing pelvic sepsis. The symptoms are generally more gradual, and the patient may have anal pain but generally no infectious symptoms. Prior to the closure of the temporary loop ileostomy, mild stenosis is expected, but it may be easily dilated at the closure operation. A pouch–vaginal fistula generally presents with isolated vaginal dis- charge or urinary tract infections. Pouchitis is the most common long-term complication of IPAA. The symptoms are similar to pelvic sepsis and may include fevers, abdominal cramping, and diarrhea; however, this will occur much later in the clinical course. Pouchitis occurs in up to 25% of patients with an IPAA. It is usually treated with oral antibiotics and resolves quickly. Some patients have many recurrences or chronic inflammations. Crohn’s disease in the pouch occurs about 4% of the time and should be ruled out as a cause of abscesses, fistulas, and pouchitis.

Answer 169

ANSWER: B COMMENTS: Endoscopic polypectomy is an effective treatment that spares selected patients the morbidity of surgical resection in the treatment of advanced polyps. Most pedunculated polyps can be resected endoscopically. Large sessile polyps are more difficult to remove. Most can be safely removed in several pieces with no impact on recurrence, as long as the margins are clear. All polyps undergo a complete pathologic examination after excision to determine not only whether the polyp is completely resected but also if high-risk factors are present that may indicate a higher likelihood of residual disease, lymphatic spread, or risk of recurrence. Adenomas harbor a higher risk of malignancy than nonadeno- matous polyps. Hyperplastic polyps harbor no risk, and serrated polyps are in between. Factors that predict focal carcinoma in an adenomatous polyp include increased size, high-grade dysplasia, and villous versus tubular structure. Factors that are associated with an increased risk of spread when there is a focus of cancer are high tumor grade (poorly dif- ferentiated), penetration into the submucosa or deeper (T1 or greater vs. in situ location in the mucosa), lymphovascular inva- sion, and resection margin of less than 2 mm. Many of these patients will undergo surgical resection. In the absence of these factors, the metastatic spread would be exceedingly rare. Piecemeal removal of large polyps presents a problem since it may be impossible to determine if the resection margins are clear. Polyps of the rectum are considered more aggressive and require a more complete excision. A full-thickness transanal excision, with clear margins using either standard operating anal retractor for low lesions or TEM is recommended.

Answer 170

ANSWER: C COMMENTS: Ogilvie’s syndrome was first described by Sir William Heneage Ogilvie in 1948. This is a syndrome of obstipa- tion, acute distention, and dysmotility or ileus of the colon without evidence of a mechanical obstruction. It is associated with the use of opiates and neuroleptic medications, diabetes, myxedema, sclero- derma, uremia, hyperparathyroidism, lupus, Parkinson’s disease, retroperitoneal hematomas, and severe metabolic illnesses. It is commonly encountered in immobile hospitalized patients after orthopedic or neurosurgical procedures. Its pathophysiology is not clear but may involve an imbalance in autonomic neural function of the colon distal to the splenic flexure that results in a contraction of the distal part of the colon and functional obstruction. Frequently, the right and transverse sections of the colon are dilated compared with the distal colon. The risk of ischemia rises when the cecal diameter reaches 12 cm or more. If the patient is hemodynamically stable, without peritonitis, and without a known mechanical obstruc- tion, initial management includes hydration, mobilization, correction of any electrolyte abnormalities, avoidance of offending drugs such as opiates, placement of a nasogastric tube if the stomach or small bowel is distended, tap water enemas, and serial abdominal examinations. Mechanical obstruction should be ruled out with a contrast enema or colonoscopy. Colonoscopy may be both diagnostic and therapeutic; it will rule out a mechanical problem such as carcinoma or volvulus, and decompression of the colon or reduction of a volvulus may be performed. Seventy percent of patients will improve with conservative treatment in the first 48 h. Neostigmine or colonoscopy should be considered if conservative treatment fails. Neostigmine is a cholinesterase inhibitor that produces colonic contraction; however, it can also cause bradycardia. All patients receiving neostigmine must be placed on a cardiac monitor, and atropine must be readily available to treat significant bradycardia. Placement of a rectal tube is rarely effective because the dilation is primarily in the proximal colon. Colonoscopy to the transverse colon is adequate for suction decompression. Colonoscopy may need to be repeated. Patients who fail nonoperative measures should be considered for surgical treatment such as cecostomy or resection if the cecum or right colon is compromised, ischemic, or perforated.

Answer 171

ANSWER: C COMMENTS: Screening asymptomatic, average-risk patients for CRC with adenomatous polyp removal has been clearly shown to reduce the incidence of CRC and to increase the number of early cancers detected versus advanced cancers. However, screening must be accomplished in a cost-effective manner that encourages patient compliance. Screening tests mainly take the form of FOBT, flexible sigmoidoscopy, and colonoscopy. The test that most easily accomplishes the goals of compliance and cost-efficacy is an annual examination of the stool for occult blood (FOBT). This test uses the peroxidase-like activity of hemo- globin. Three separate stool samples are collected on a guaiac paper, and hydrogen peroxide is added; if hemoglobin is present to catalyze the reaction, the colorless guaiac is oxidized to a blue-colored quinone. Normal blood loss in the stool is 2 mg of hemoglobin/g of stool; FOBT requires fecal blood loss of 10 mg of hemoglobin/g of stool to obtain a positive result. However, the sensitivity of FOBT is as low as 50%–85% in patients with known cancers. Mass screening programs with FOBT will yield positive results in 1%–8% of patients. The positive predictive value of a positive test result is 10% for cancer and 30% for adenoma. These programs diagnose a higher percentage of early localized cancers than may be expected otherwise, indicating the usefulness of such an approach. The risk reduction in CRC mortality ranges widely depending on the study and the type of FOBT used. Estimates range from 18% to 55%. Combining annual FOBT with periodic flexible sigmoidoscopy every 5 years provides a greater risk reduction. Flexible sigmoidoscopy provides an effectiveness of approximately 34%–66%; effectiveness is increased in combination with annual FOBT. The benefits of this regimen above colonoscopy lie in a shorter, less costly procedure that does not require oral bowel preparation. Flexible sigmoidoscopy is estimated to detect 70% of lesions present. When combined with FOBT, it provides reasonable sensitivity for the screening of a large population. Double-contrast barium enema provides an alternate means of screening with an effectiveness of 33%–47%. It may provide improved visualization in colons with multiple strictures than flex- ible sigmoidoscopy or colonoscopy. It is generally used in conjunction with flexible sigmoidoscopy. CT colonography (formerly called “virtual colonoscopy”) was introduced in 1994. Like colonoscopy, it requires a bowel preparation. Air is insufflated into the colon followed by thin-cut images in a CT scanner in the prone and supine state. Three-dimensional reconstruction of the entire colon and the use of a “fly-through” view result in kinetic images that may allow better visualization behind the haustral folds than colonoscopy. However, only lesions greater than 1 cm are reliably seen, and residual stool may not be well differentiated from significant findings. Although CT colonography is effective as a screening tool versus no screening, it is not as effective as colonoscopy, it costs substantially more to achieve reasonable effectiveness, and it is not therapeutic since polypectomy and biopsies cannot be performed. Therefore it is primarily used in patients who cannot tolerate a colonoscopy or in patients with an incomplete colonoscopy because of difficult passage or obstruction. Colonoscopy remains the screening test of choice since it is highly sensitive and specific as well as diagnostic and therapeutic. Colonoscopic screening has been shown to be the most effective method of risk reduction. Studies have shown 60%–90% reduction in the incidence of CRC in patients who are screened appropriately. Although complication rates are higher than other methods, the rate of perforation and significant bleeding is only 4 of 10,000 or 0.04%. Current screening practices for asymptomatic patients endorsed by the American Cancer Society consist of the following: • High-sensitivity FOBT with three consecutive stool samples yearly • Flexible sigmoidoscopy every 5 years with FOBT every 3 years • Colonoscopy every 10 years Colonoscopy is also used as a diagnostic test when a person has symptoms, and as a follow-up test when the results of another screening test are unclear or abnormal.

Answer 172

ANSWER: C COMMENTS: Rectal prolapse is a pelvic floor disorder that is most commonly found in women, with a 6:1 female-to-male ratio. This disorder has a bimodal distribution of incidence, with peak onsets within the first 3 years and after the seventh decade of life. There are varying degrees of prolapse—internal intussusception or occult rectal prolapse (or prolapse of the rectal wall without protrusion through the anus), procidentia (or complete protrusion of all layers of the rectum), and mucosal prolapse. Rectal prolapse is differentiated from incarcerated internal hemorrhoids by a close examination of the mucosal folds. Incarcerated internal hemor- rhoids have a radially invaginated tissue, which distinguishes the hemorrhoidal cushion beds. Rectal prolapse has concentric (target) folds. The pathophysiology of rectal prolapse is not clear, but several typical abnormalities have been identified. The normal rectal mes- enteric attachments to the sacrum are lost, and the rectum sags down into the deep pelvis. Defecography studies have demonstrated that weakness of the pelvic floor allows full-thickness intussusception of the rectum through the anal canal and levator hiatus. Pudendal nerve injury due to stretching of the nerve in the ischiorectal fossa between its fixed exit from Alcock’s canal and insertion into the sphincter muscles contributes to pelvic floor weakness. Direct trauma, obstetric injury, neuropathic diseases, such as diabetes, and neoplasms involving the sacral nerve root can all lead to pudendal nerve damage. Although neoplasm is a common cause of adult small bowel intussusception, it is not usually the cause of intussusception in rectal prolapse. The most common symptom is the sensation of an anal “mass” that reduces with manual pressure. Protrusion usually occurs with increased abdominal pressure such as during coughing or defecation. Fecal incontinence is a predominant symptom that is seen in 50%–75% of patients with rectal prolapse. Other symptoms include tenesmus and rectal pressure. Internal intussusception often presents with rectal pressure and obstructed defecation. It is best demonstrated by cine defecography. Operative repairs for rectal prolapse can be done through either an abdominal or a perineal approach. The abdominal approach usually involves the resection of redundant sigmoid colon and rectopexy. This approach is generally reserved for healthier patients who can tolerate abdominal surgery. Either an open or minimally invasive approach can be used. The recurrence rate is low. The Altemeier procedure is a perineal approach that includes proctosigmoidectomy with a full-thickness resection of the redundant rectum and a variable amount of sigmoid while prolapsed. A levatorplasty is also often performed with this procedure to tighten the anal hiatus. Other repairs include the Delorme procedure (mucosal resection with plication of the rectal wall), rectopexy alone, rectopexy with mesh, and a Thiersch loop. Procedure selection is highly dependent on the extent of prolapse and the physiologic condition of the patient.

Answer 173

ANSWER: C COMMENTS: The causes of lower GI bleeding are many; it is accounted for predominantly by diverticular disease or angiodysplasia (60%), IBD (13%), anorectal disease such as hemorrhoids and fissures (11%), and neoplasia (9%). Few of these lead to massive bleeding. Frequently found to coexist, diverticulosis and angiodysplasia are responsible for most cases of massive colonic bleeding. The cause of angiodysplasia, or vascular ectasia, is unknown, but it may be related to degenerative vascular changes associated with aging and to colon wall muscular hypertrophy that obstructs the submucosal veins and leads to dilation and a propensity of these veins to bleed. Most cases of colonic angiodysplasia are located in the cecum and right colon. They may also be found in the small bowel, especially the terminal ileum. In contrast to diverticular disease, bleeding from angiodysplasia is venous and not as severe. Diverticulosis can also cause massive bleeding due to ruptured vasa recta in the neck of a diverticulum. Superficial mucosal ulceration in diverticula usually causes mild and self- limited bleeding. Ulcerative colitis is more likely to cause mild-to- moderate bleeding and is frequently associated with diarrhea and systemic signs of chronic illness such as weight loss and failure to thrive. Cancer of the colon generally causes occult rather than massive GI bleeding, with slow blood loss in stools rather than marked bright red blood or melena. Ischemic and infectious colitis may present with mild bleeding usually associated with abdominal pain and fevers, if infectious, or diffuse central or peripheral vascular disease, if ischemic.

Answer 174

ANSWER: A COMMENTS: Toxic megacolon is most commonly seen in patients with IBD. Classically, it presents acutely in patients with ulcerative colitis (∼5%) and less frequently in those with Crohn’s colitis. Although the incidence of toxic megacolon is decreasing in IBD because of better medical management, it may also occur with severe Clostridium difficile colitis that is increasing. Toxic megacolon is a subset of toxic colitis. Both cause critical illness and can lead to perforation, peritonitis, and death. The diagnosis of toxic megacolon is based on the clinical findings of fever, tachycardia, and abdominal distention, combined with radiographs showing colonic distention to 6 cm or greater and leukocytosis greater than 10.5 × 103/L. Successful management is predicated by early recognition and aggressive treatment. Immediate surgery is required for perforation and peritonitis. Otherwise, the patient is admitted to the intensive care unit for rapid fluid resuscitation, transfusion of blood products if needed, and nasogastric suction to minimize the accumulation of swallowed air in the colon. Air usually accumulates preferentially in the transverse colon as opposed to the cecum with distal colon obstruction, and this may be promoted by patients lying supine. Prompt administration of steroids is still felt to be an important component of therapy, and broad-spectrum antibiotics are routinely administered. Response to medical management is assessed with serial vital signs and abdominal radiographs. Colonoscopy is not necessary in patients with known IBD since attempts at decompression are not helpful and intubation of the already tenuous and friable colon may cause perforation. In patients with no previous history of IBD, a careful proctoscopy to 10 to 15 cm with little insufflation is generally adequate to confirm IBD. Infliximab is an anti-TNF-α antibody that blocks the TNF-α receptor, which in turns decreases inflammation. It is used to reduce the signs and symptoms of IBD and maintain remission. Infliximab is not used in the setting of acute toxic megacolon related to IBD. Worsening colonic distention, fever, and leukocytosis are indications for urgent surgery. The operative procedure of choice is abdominal colectomy and ileostomy without proctectomy. The rectum or distal sigmoid may be closed as in a Hartmann’s procedure. If the sigmoid is weak or thinned out, it may be exteriorized through the lower end of the midline incision, wrapped in wet gauze, and matured several days later at the bedside as a mucous fistula (Jones procedure). Total colostomy with preservation of the rectum allows a sphincter-preserving operation, usually an IPAA procedure, to take place once health has been restored. Even when medical therapy of toxic colitis and megacolon is successful, most patients do not have a satisfactory long-term outcome and will require colectomy within the next 6 to 12 months for ongoing symptoms and even recurrent toxic colitis.

Answer 175

ANSWER: D COMMENTS: Different colonic diseases have different indica- tions for and contraindications to colonoscopy. Rectal bleeding: Patients with melena, hematochezia, other blood loss in the stool, and iron deficiency anemia of unknown etiology should always undergo evaluation of the entire colon, even if the patient is thought to have an anorectal source. Although bleeding from hemorrhoids, fissures, and other anorectal causes is quite common, it does not usually result in anemia, and a malignant source should always be ruled out. IBD: Endoscopy aids in the diagnosis of IBD; however, it is not indicated for assessment of response to medical therapy, which can be done based on clinical findings alone. Patients with a history of ulcerative colitis for more than 8 to 10 years are at a higher risk for developing adenocarcinoma of the colon; their risk increases 1%–2% per year after 10 years. Therefore they should undergo regular surveillance colonoscopy with multiple biopsies to monitor for dysplasia, a known marker for increased cancer risk in IBD. This should be done even if the disease is in remission. The risk of cancer in patients with Crohn’s disease is less well understood. It is likely that patients with pancolitis due to Crohn’s disease probably have similar rates of cancer as do chronic ulcerative colitis patients. However, most Crohn’s patients have segmental rather than diffuse colonic disease and so the risk may be relatively lower. Colonoscopy should not be performed during acute manifestations of IBD because of the potential for colonic perforation. Ischemic colitis/diverticulitis: Colonoscopy is contraindicated in patients with acute peritoneal inflammation such as acute diverticulitis, peritonitis, or perforation. Colonoscopy may be per- formed after the acute inflammation has resolved to evaluate for cancer, polyps, or other causes of symptoms. Volvulus/pseudo-obstruction: Colonoscopy is indicated for patients with sigmoid volvulus or pseudo-obstruction of the colon for decompression and to rule out other causes of symptoms, provided that there are no signs of peritoneal inflammation. Colonoscopic decompression of a cecal volvulus is usually not successful. Routine screening: Screening begins at age 50 in the average- risk population and continues at 10-year intervals until age 75. Screening after this age is controversial. Colonoscopy is the gold standard since it is both diagnostic and therapeutic. Polyps may be removed and larger lesions may be biopsied. If polyps are found and removed, surveillance colonoscopy should be performed at more frequent intervals because of increased risk. CT colonography (formerly known as virtual colonoscopy) is useful in patients in whom colonoscopy was incomplete because of a tortuous sigmoid colon or pain. If there is any suspected lesion, a colonoscopy must be performed. If an adenomatous polyp or cancer is discovered during screening sigmoidoscopy, colonoscopy is indicated to exclude the possibility of proximal synchronous polyps (30%) or cancer (4%–8%). Increased risk screening: Colonoscopy should be performed earlier and more frequently in patients with a known family history of cancer, such as HNPCC, FAP, and those having first-degree rela- tives with colon cancer. In general, patients with first-degree relatives with polyps or colon cancer should initiate screening at age 40 or 10 years younger than their relative’s age of diagnosis; screening interval is dictated by the age of the affected relative, with younger age signifying increased family risk.

Answer 176

ANSWER: A COMMENTS: Backwash ileitis consists of nonspecific inflamma- tion and dilation of the ileum in patients with ulcerative colitis involving the entire colon. There is no thickening or narrowing as seen in Crohn’s disease. Its presence does not imply a pre-Crohn’s disease condition, nor does it imply a poor outcome after the IPAA procedure. It will resolve once the ulcerative colitis is treated. Diversion colitis is found in segments of defunctionalized bowel, usually distal to a diverting ostomy or after a Hartmann’s procedure. Colon epithelial cells seem to require nutrients from the luminal contents passing by, including short-chain fatty acids. Diversion colitis is thought to result when colonocytes are deprived of these compounds. This is supported by the observation that instillation of short-chain fatty acids ameliorates this condition. Preliminary trials on idiopathic ulcerative proctocolitis have shown a response to short-chain fatty acid enemas. Following reversal of the fecal diversion, the endoscopic findings of diversion colitis usually resolve. Microscopic colitis (also known as lymphocytic colitis) is characterized by a history of watery diarrhea and microscopic inflammation of the colonic mucosa. The colitis often responds favorably to sulfasalazine. Collagenous colitis (which exhibits a collagenous band under the surface epithelium of the colon on a microscopic examination) may be a variant of this condition because patients have similar symptoms and also respond to sulfasalazine. Spontaneous remission of these two conditions is common. Most of these patients have been incorrectly labeled for years as having irritable bowel syndrome. Colonoscopy with biopsy may yield the correct diagnosis. Campylobacter causes a diarrheal gastroenteritis that is often self-limited. However, it can cause severe dysentery, especially in a weakened host. It responds well to macrolide antibiotics including erythromycin, clarithromycin, or azithromycin. Acute inflammatory ileitis causes right lower quadrant pain and is commonly confused with appendicitis or Crohn’s disease. Acute ileitis may be due to infection with Y. enterocolitica. It is often self-limited but may be treated with antibiotics. It is often resistant to penicillin but is sensitive to aminoglycosides, sulfa- methoxazole and trimethoprim (TMP-SMZ, Bactrim), ciprofloxacin, and doxycycline. Antibiotic-induced colitis (also known as pseudomembranous colitis) is characterized by watery diarrhea, which is rarely bloody and is caused by the proliferation of C. difficile. The diagnosis is best made by detecting C. difficile toxin in the stool. Either oral vancomycin or metronidazole is used to treat this condition. The latter is less expensive and is therefore used more often.

Answer 177

ANSWER: E COMMENTS: Most reports of FAP syndromes reflect experience in American and European populations, but these diseases have been identified in Africans and Asians as well. There is probably no race or geographic area that is exempt. These polyposis syndromes occur in approximately 1 in every 10,000 births. The disease is transmitted as an autosomal dominant trait, and therefore 50% of the offspring of an afflicted individual will have the disease. About 30%–40% of familial polyposis patients do not have a family history of polyposis, and these cases represent spontaneous mutations in the APC gene. FAP is the causative factor in about 1%–2% of all CRCs. The polyps are not present at birth but usually first appear at puberty and gradually increase in number so that by the age of 21, the colon and rectum are carpeted by thousands of polyps. If left untreated, virtually all patients will develop CRC by 40 years of age. Some patients will also develop duodenal and jejunal polyps, which can be very difficult to manage. Periampullary cancer develops in about 5% of patients, primarily when they already have extensive duodenal polyps. Surgical management is primarily aimed at reducing the risk of CRC. Since most patients will develop cancer by age 40, prophylactic colectomy is recommended in the teens to early 20s. The most common approach is proctocolectomy with anal mucosectomy to the dentate line and reconstruction with an IPAA. This procedure removes all of the at-risk colorectal mucosa while avoiding a permanent ileostomy. Abdominal colectomy with IRA is still recommended occa- sionally since it is a relatively straightforward procedure and pelvic dissection is avoided. It is only appropriate if there are less than 20 polyps in the rectum and they can be cleared preoperatively. However, close surveillance of the rectal remnant by proctoscopy every 6 months is mandatory. The incidence of rectal cancer after IRA varies widely among series, probably because of variations in surveillance compliance. Rates of 10%–60% have been published from reputable institutions. In fact, patients are less likely to die of rectal cancer than of periampullary tumors or desmoids. Nevertheless, the importance of surveillance proctoscopy cannot be over- emphasized. IRA should not be considered if there are large or dysplastic rectal polyps, or if the patient already has a colon cancer. Attenuated FAP (aFAP), defined as between 20 and 100 polyps, is relatively uncommon. It seems to be due to mutations in a different part of the APC genome that is typical of FAP. Although there is a somewhat lower rate of cancer, it is still a high-risk mutation, and surgical management is usually recommended. An IRA procedure may be appropriate in many patients with aFAP. Patients with a family history of FAP should be screened with flexible sigmoidoscopy starting at puberty. Annual sigmoidoscopy is recommended until age 20. Genetic screening is also available but is not 100% accurate, and therefore does not replace sigmoidoscopy. Colonoscopy is not necessary since all affected patients will have rectosigmoid polyps. Upper GI endoscopy screening should be performed to look for involvement of the stomach and duodenum every 1 to 3 years beginning at the age of 20 to 25. All polyps should be removed, if possible.

Answer 178

ANSWERS: A-c, B-a, C-d, D-b, E-e COMMENTS: The APC gene is located on chromosome 5, is large (consisting of approximately 15 exons), and encodes for a cytoplasmic protein of 2843 amino acids. APC mutations occur in patients with both sporadic CRCs and familial polyposis, are frequent, are comparable in incidence with adenomas and carcinomas, and occur early in the development of cancer. The protein product of the APC gene is normally involved in maintaining cellular adhesion and sup- pressing neoplastic growth, but the mutant protein may not be capable of serving this function. The APC gene thereby acts as a tumor-sup- pressor gene. Approximately 35% of patients with sporadic cancers and up to 75% of those with polyposis cancers have APC mutations that can occur at variable points within the gene. This may explain the various phenotypes associated with the polyposis syndromes. The p53 gene is a tumor-suppressor gene located on chromosome 17. Mutations of this gene are the most common genetic abnormality found in various human cancers. The gene encodes for a nuclear phosphoprotein that regulates transcription and nega- tively influences cellular proliferation by binding at specific DNA sites. For example, cells damaged by ultraviolet light or radiation are kept from replicating by the wild-type (natural) p53 protein. Mutant p53 binds to wild-type p53, thereby preventing specific binding to DNA and permitting tumor growth. Mismatch repair genes correct errors of DNA replication. Alterations in these genes have been implicated in the pathogenesis of HNPCC. The genetic mutations identified are (1) MSH2 on chromosome 2 (mutation of this gene may account for up to 60% of the genetic alterations seen in families with HNPCC); (2) MLH1 on chromosome 3, which may act as a tumor-suppressor gene; (3) MSH6 on chromosome 2; (4) PMS1 on chromosome 2; and (5) PMS2 on chromosome 7. Mutations of the latter two genes account for only 10% of the mutations seen in families with HNPCC. Germline mutations of the hMSH2 and hMLH1 genes by themselves are not enough to produce the HNPCC phenotype. A somatic mutation of the remain- ing wild-type allele is also necessary. The DCC gene is located on chromosome 18 and is one of the first mutations found to be associated with colon cancer. It encodes for a protein involved in cell-to-cell contact. Deletions of this gene have been found in 73% of patients with CRCs but in only 11% of those with adenomas, thus suggesting that gene loss occurred late during tumorigenesis. Cancers with the loss of the DCC gene are more likely to initially be seen as an advanced disease (in compari- son with tumors maintaining this gene), and patient survival is consequently compromised. The Kras gene, an oncogene found on chromosome 12, encodes for a plasma membrane–based protein involved in the transduction of growth and differentiation signals. Approximately 50% of patients with CRC have Kras mutations. Large adenomas and adenomas with small areas of invasive cancer have nearly the same incidence of Kras mutations, thus suggesting that genetic alterations in the Kras gene occur early (but not as early as APC mutations) during tumorigenesis. It has yet to be proved whether Kras mutations have any prognostic significance.

Answer 179

ANSWER: A COMMENTS: By definition, this lesion is classified as carci- noma in situ or intramucosal adenocarcinoma and is treated adequately by endoscopic polypectomy. Because a lymphatic plexus exists just below the muscularis mucosae, lymphatic dissemination is possible only when invasion deep to this level has occurred. The muscularis mucosae of the colon wall may extend for a vari- able distance into the stalk of the polyp and may not even reach the head. Pedunculated polyps consist of four anatomic levels: Haggitt’s level 1 is the head itself, level 2 is the interface between the head and the stalk, level 3 is the stalk, and level 4 is the junction between the stalk and the colonic wall (Fig. 23A.2). Endoscopic polypectomy should be considered adequate treatment for a polyp containing invasive cancer at level 1, 2, or 3, if the carcinoma is well differentiated and does not exhibit invasion of the veins or lymphatics and the resection margins are free of cancer. For example, endoscopic polypectomy would be sufficient for a tubular adenoma with well-differentiated cancer extending to level 3 as long as there was no evidence of venous or lymphatic invasion and the margin of resection was free of disease. However, a poorly differentiated cancer extending to level 2 would require formal segmental resection either minimally invasive or by open means. Similarly, any polyp with cancer extending to level 4 requires segmental resection, regardless of differentiation or vascular invasion. Laparoscopic colectomy is now widely accepted as equivalent to open operation for the cure of colon cancer when performed by experienced surgeons. The Clinical Outcomes of Surgical Therapy (COST) Study Group performed a randomized controlled trial com- paring open colectomy with laparoscopically assisted colectomy and found no difference in intraoperative complications, reopera- tions, survival, and tumor recurrence. However, this patient does not need any further treatment other than observation and subsequent endoscopic surveillance.

Answer 180

ANSWER: A COMMENTS: Of the many variables that affect the cure of patients with colon cancer, the status of the lymph nodes has con- sistently remained the most important. Even with modern aggressive therapy, the long-term survival of node-positive patients is approximately one-half that of node-negative patients. The extent of nodal disease also has an impact on the prognosis. Patients with four or more positive lymph nodes have a significantly lower 5-year survival rate than do patients with three or fewer positive nodes. Tumor size in and of itself has no bearing on metastatic potential or prognosis. The DNA content of colorectal tumors has been studied extensively, and aneuploidy seems to correlate well with histologic differentiation, transmural penetration, and the presence of nodal metastases. However, the DNA content in general has not been shown conclusively to be an important independent prognostic indicator. Microsatellite instability is associated with inherited cancers but has also not been shown conclusively to be an independent prognostic indicator. A meta-analysis of 32 eligible studies involving 7642 patients noted that only about 15% of the CRC population had microsatellite instability reflecting inactivation of mismatch repair genes. In the remainder of the colorectal population (85%), colon cancer developed from other pathways and included aneuploidy, allelic losses, amplifications, and transloca- tions. In this study and other studies, microsatellite instability was actually associated with a better prognosis in stage II cancers.

Answer 181

ANSWER: E COMMENTS: Staging of rectal cancer has evolved over the past few years. Accurate staging helps determine appropriate treatment and predicts outcomes. EUS has been used for several decades and is generally performed as an office procedure without the need for sedation or formal bowel preparation. Both rigid probes and endoscopic mounted devices are available. A single enema is given 1 to 2 h before the examination to remove any stool from the rectal vault. Because only a minimal penetration of the rectal wall and perirectal tissues is required, a high-frequency ultrasound crystal is used (i.e., 7 or 10 MHz) to obtain a high resolution of the superficial structures. It is possible to image lesions in the mid and upper portions of the rectum, but to be certain that the ultrasound probe is in contact with neoplasms at this level, it is necessary to insert the probe under direct vision through a 2-cm-wide proctoscope. EUS is used to stage rectal cancer. It is superior to CT for locoregional staging and has an overall accuracy for predicting tumor stage of up to 80%–95% as compared with CT, which is 65%–75% accurate. EUS also provides the benefit of guiding fine- needle aspiration biopsies to improve the accuracy of nodal staging. EUS demonstrates the depth of invasion of cancer (T stage) and nodal involvement (N stage). For endoscopic ultrasound to be accurate on staging lymph nodes, the nodes must be at least 5 mm. Interobserver variability in performing EUS can be a limitation. In addition, EUS is limited in restaging patients treated with neoadjuvant chemotherapy and radiation therapy because of the treatment-induced fibrosis. Therefore a complete staging with CT of the chest, abdomen, and pelvis; magnetic resonance imaging (MRI) of the pelvis; and examination under anes- thesia (EUA) in earlier cases should be performed before initiating treatment. Ultrasound staging is as follows: uT1 is confined to the mucosa and submucosa, uT2 invades but does not penetrate through the muscularis propria, uT3 invades into the perirectal fat, uT4 invades into adjacent organs, uN0 has no lymph node enlarge- ment, and uN1 has lymph node enlargement. Image-guided needle biopsy of extraluminal nodules is a safe procedure that can be performed under ultrasound guidance; suspicious perirectal nodules can also undergo a biopsy in this fashion. Only if the biopsy specimen contains benign lymphoid tissue can it be assumed that the nodule in question is truly free of cancer. Pelvic MRI is now part of the recommended staging protocol. It is better at staging larger lesions, looking for extrarectal extension and venous, sacral, and pelvic side wall involvement. The likelihood of obtaining clear circumferential margins may also be predicted. EUS is more accurate for the staging of early lesions— T1 versus T2—and therefore it is very useful for deciding on local treatment for T0 and T1 lesions versus radical treatment for T2 and greater tumors.

Answer 182

ANSWER: C COMMENTS: Multiple studies have shown that radiation therapy to the pelvis decreases the rate of local and regional recurrence and that systemic chemotherapy reduces the rate of systemic progres- sion. Preoperative combined chemotherapy as opposed to postoperative treatment is associated with lower complication rates and better clinical function. A variety of protocols have been studied globally. In the United States, a full-course radiation therapy con- sisting of about 5000 cGy to the pelvis and regional lymph node basins for over 6 weeks with a final boost to the primary tumor region with synchronous 5-fluorouracil (5FU)-based chemotherapy is standard. Radical resection of the rectum and mesentery with the lymph nodes by either APR with a permanent colostomy for low rectal lesions or LAR with anastomosis and temporary diverting loop ileostomy is performed 6 to 10 weeks following completion of the neoadjuvant therapy. After recovery from the operation, 6 to 12 months of chemotherapy are given, depending on the final pathology. Recent data show that up to 20% of patients will have a complete pathologic response to neoadjuvant treatment, meaning that no residual tumor is found in the resected specimen. However, a patient with a complete response cannot be reliably predicted based on current clinical evaluation or imaging. Therefore all patients proceed to resection unless they are medically unfit or refuse. Short-course neoadjuvant therapy with 2500 cGy given for over 1 week followed by surgery 1 week later is used in some centers in Europe but is not standard in the United States. No trials have yet shown that the short-course therapy is as good as the long- course treatment. This patient has stage III rectal cancer based on pretreatment clinical staging, which shows T3 invasion (through the muscularis propria), three enlarged perirectal lymph nodes (N1), and no evidence of distant spread (M0). Full neoadjuvant treatment with subsequent surgery is appropriate. LAR with a coloanal anastomosis is likely to be technically possible since a 2-cm margin from the anorectal ring should be achievable. Therefore APR is not necessary. In stage III patients, neoadjuvant therapy is associated with a significant increase in survival from 30% with surgery alone to 60%–70% with combined therapy.

Answer 183

ANSWER: D COMMENTS: The most common symptom of rectal cancer is hematochezia. Other symptoms include mucus discharge, tenes- mus, and changes in bowel habits, often with a thin, pencil- or ribbon-like appearance. The workup for rectal cancer includes complete colonoscopy to exclude synchronous colon tumors, CT of the chest, abdomen, and pelvis, MRI of the pelvis, and EUA in selected patients who may be candidates for local treatment. The precise location is best determined by rigid proctosigmoidoscopy, which should be done even if the tumor has been diagnosed with colonoscopy to accurately assess orientation of the tumor and the level above the anal canal. The upper end of the anal canal is the anorectal ring that is typically 1 to 2 cm above the dentate line. This is the lowest level that resection may be performed without sacrificing the anal sphincters. A 2-cm margin is recommended since studies have shown that intramu- ral spread of cancer below the visible and palpable margin is rarely beyond 1 cm. Measurement of CEA levels is standard. Normal CEA levels are up to 5 μg/L. In smokers, they may be up to 7 μg/L. Although CEA levels are not useful for screening since only 70% of cancers express this antigen and levels are often normal in localized lesions, they are useful for follow-up. A baseline level is always drawn prior to initiating treatment. Very high levels, in the hundreds to thousands, are associated with metastatic disease. If the CEA is elevated and it normalizes after treatment, it may be useful for detecting recurrence. CEA levels are routinely checked every 3 months for several years. Transanal excision is not part of the initial evaluation of rectal cancer and should be considered only after the evaluation is complete so that the appropriate treatment approach can be selected. Preoperative clinical TNM staging (Table 23A.1) as well as the level of the lesion in the rectum guide therapeutic decisions. Stage I tumors do not require neoadjuvant therapy (preoperative radiation and chemotherapy). Ultrasound-staged T1 tumors can be treated with transanal local excision: either standard transanal excision with conventional operating anoscopes, TEM, or TAMIS using laparoscopic instruments. TEM uses carbon dioxide insufflation through a 40-mm operating rectoscope and a binocular mag- nifying visual system to create a better endoscopic visualization of the operative field. TEM is more likely to yield negative margins, an intact specimen, and lower recurrence than operations using conventional transanal instruments. The pitfall with any transanal approach is an inability to assess lymph node status. In T1 cancers, the incidence of lymphatic metastases is about 5%, and the outcomes of local excision versus radical excision are the same. Therefore they are considered safe for transanal excision. Ultrasound-staged T2 rectal cancers should undergo radical surgery because of the significant risk of lymph node metastases (25%–30%). The ultrasound image of this patient showed penetration of the muscularis propria and possibly the mesorectal fat. Suspicious lymph nodes (spherical, hypoechoic) are seen as well. Therefore she is clinical stage III and should undergo neoadjuvant chemora- diation therapy before radical surgery. APR involves a complete excision of the rectum and anus through a combined abdominal and perineal approach. APR leaves the patient with a permanent colostomy. Thus APR is indicated when the patient has poor preoperative sphincter control, the patient’s body habitus is unfavorable, the tumor involves the anal sphincters, or part of the sphincter needs to be resected to obtain negative margins (as in a tumor less than 2 cm from the anorectal ring). LAR involves excision of the rectum and mesorectum through an abdominal approach and colorectal or coloanal anastomosis. A temporary loop ileostomy is often used to protect the low colorectal anastomosis, especially in radiated patients because of the higher risk of anastomotic leak. In the United States, stages II and III rectal cancers are com- monly treated with full-course neoadjuvant (preoperative) radiation therapy consisting of 5040 cGy and 5-FU-based chemotherapy. Fulguration is rarely used in current surgical practice because of the advances in transanal excision that provides a full-thickness specimen for pathology staging. It may be used in patients with small lesions below the peritoneal reflection that are poor surgical candidates or for small recurrences.

Answer 184

ANSWER: E COMMENTS: Evidence shows that the incidence and virulence of C. difficile are increasing. Metronidazole and oral vancomycin have been known to be effective therapies for C. difficile since the late 1970s. IV vancomycin is ineffective in treating C. diffi cile colitis. A review conducted before 2000 showed that the failure rate of metronidazole for treatment of C. difficile colitis was 2.5% and the failure rate of treatment with oral vancomycin was 3.5%. Since 2000, there has been an increase in this failure rate, with recent data showing a metronidazole failure rate of 18.2%. Newer data also show that both agents still have similar efficacy in mild infection, but that vancomycin has superior efficacy in severe infection. Rectal administration of vancomycin may be employed as a treatment modality in severe infections and in patients who cannot tolerate oral administration as in the case of this patient with a postoperative ileus. Dual therapy of IV metronidazole and vancomycin may be employed in severe infections as well.

Answer 185

ANSWER: C COMMENTS: CRC is the third most commonly diagnosed cancer and the second leading cause of cancer death in men and women combined in the United States. Approximately 5% or 1 in 20 Amer- icans will be diagnosed with a cancer of the colon or rectum in their lifetimes. There are approximately 150,000 new cases of CRC in the United States per year. CRC rates are highest in black men and women and lowest in Asian/Pacific Islander men and women. The incidence and death rates of CRC increase with age. Overall, 90% of new cases and 93% of deaths occur in people aged 50 years or older. Mortality rates are 30%–40% higher in men than in women. The median age of colon cancer diagnosis is 69 in men and 73 in women. The median age of rectal cancer diagnosis is 63 in men and 65 in women. CRC death rates have been declining since 1980 in men and since 1947 in women, and this can be attributable to improved screening, treatment, and decreases in exposure to risk factors.

Answer 186

ANSWER: D COMMENTS: Extracolonic manifestations of FAP include adenomas of the upper GI tract, desmoid tumors, osteomas, pigmented lesions of the retina, and epidermoid cysts, as well as gastric, thyroid, suprarenal, and central nervous system cancers. The patient in this scenario has a desmoid tumor of the small bowel mesentery. This is a typical presentation of a patient with a history of FAP and the finding of an intraabdominal soft tissue mass. Desmoid tumors are benign growths that occur in 10%–20% of patients with FAP. They are a form of fibromatosis and are more common in patients with a family history of desmoids. Histologically, they consist of proliferating myofibroblasts. They have no malignant potential but often progress locally, infiltrating tissues and causing obstruction, vascular compromise, and pain. They are most commonly found in the abdomen, particularly in the small bowel mesentery, in the retroperitoneum, and in the abdominal wall. Occasionally they will develop in other sites. Desmoids are the second most common cause of death in patients with FAP, after GI malignancies. Most desmoids grow slowly and may cause symptoms over time; some will grow faster. Some will grow, plateau, and then regress. There are no specific inciting factors, but the observation has been made that desmoids may grow more rapidly after abdomi- nal surgery. They also have a high rate of recurrence after resection. Asymptomatic desmoid tumors demonstrating little or no growth can be observed. They should be followed with imaging to assess progression. Initial therapeutic measures are aimed at slowing growth. Several medications have been shown to be of benefit in some patients. Nonsteroidal antiinflammatory drugs (NSAIDs) such as sulindac and indomethacin have been used both to treat desmoids and to slow growth of polyps. Alone, they are not particularly effective. Antiestrogen agents such as tamoxifen and pro- gesterone seem to have more effect. Tamoxifen is currently the mainstay of medical treatment. Combined therapy with an NSAID and tamoxifen may prove to be more effective. Overall, about 50% of patients have stabilization or reduction in tumor mass with medical therapy. Cytotoxic chemotherapy is rarely used but is an option when the tumor is growing rapidly and causing symptoms, does not respond to other medical therapy, is not resectable, or recurs rapidly after resection. Typical agents include doxorubicin and carboplatin. Radiotherapy is rarely used for intraabdominal tumors because of the risks and side effects. These tumors are not particularly radiosensitive. Radiotherapy may be used for abdominal wall or extremity lesions. It also may be used as an adjuvant to surgery. Surgical excision is the most effective means of eradicating these tumors; however, recurrence rates are over 60%, and clear margins may be difficult to achieve. There also may be significant morbidity with resection, including ischemia, short-bowel syndrome, and the loss of an ileoanal pouch, if present. The most problematic lesions are those in the base of the small bowel mesentery that surround major vessels such as the superior mesenteric artery and vein. If a large abdominal desmoid is causing obstruction, then a bypass is an alternative to resection.

Answer 187

ANSWER: B COMMENTS: ERAS programs focus on many aspects of care of the surgical patient with the intent of decreasing pain and narcotic use, decreasing the length of stay, decreasing complication rates, reducing costs, and improving the overall experience. Many ERAS programs have risen in the setting of colorectal surgery. Due to the success of these programs, the concepts are being applied to other surgical specialties. Although there are variations in the details of the programs among institutions, there are well- established principles. The major elements within these enhanced recovery programs include preoperative education, multimodal analgesia (the use of epidural regional anesthesia, maximizing usage of nonopioid analgesic options, minimizing narcotic usage), limiting perioperative starvation (preoperative complex carbohydrate drinks, early refeeding), limiting intravenous fluids, maintaining normothermia, and early postoperative ambulation. Setting expectations and psychologically and emotionally supporting the patients by dedicated personnel helps. The average hospital stay after colectomy may be reduced from 5.5 to 3.5 days for laparoscopic surgery without an increase in readmission rates.

Answer 188

ANSWER: E COMMENTS: Twenty percent of patients have metastasis at the time of diagnosis, with many more developing metastatic spread throughout the course of their disease. The most common site of metastasis is the liver; 80% of stage IV patients have hepatic spread, and 40% of these do not have the extrahepatic disease. Hepatic resection for isolated liver metastases has been clearly shown to be safe and efficacious in experienced hands. The traditional guidelines for recommending liver resection (metastasectomy) for patients with stage IV CRC are: 1) three or fewer lesions 2) disease limited to one side of the liver 3) no extrahepatic disease, and 4) a willing patient who is a reasonable surgical candidate. The median survival for isolated liver metastases treated with only chemotherapy is 20 months. With hepatic resection, median survival is as much as 88% at 1 year and 43% at 5 years. The long-term survival is about 30%. Hepatic resections for colorectal hepatic metastases have become a much safer surgery over the years, with perioperative mortality of 1%-5%. The key to safety and efficacy in hepatic resections is the careful patient selection. Factors associated with poor survival include the presence of extrahepatic disease, inability to achieve a negative margin, short interval to recurrence, number and size of tumors, lymph node–positive primary, high preoperative CEA, advanced age, and significant co-morbid disease. Other modalities available for treatment of hepatic metastases include radiofrequency ablation, staged resections for bilobar disease, and preoperative portal vein embolization or ligation to induce liver hypertrophy. An evolving approach to bilobar disease is the two-step ALPPS (associating liver partition and portal vein ligation for staged hepatectomy) procedure. In the first operation, the liver is divided into two segments. The side to be retained (FLR, future liver remnant) is cleared of disease by limited resections with clear margins. The portal vein branch to the side to be removed is ligated. During the weeks following this, the FLR parenchyma undergoes remarkable hypertrophy. In the second operation a few weeks later, the planned resection is performed, leaving the hypertrophied side. This approach allows a much larger proportion of the liver to be resected, yet leaves enough for the patient to survive. Initial results are impressive, but a larger experience with longer follow-up is needed to assess its usefulness.

Answer 189

ANSWER: E COMMENTS: Colonic volvulus refers to torsion of the bowel around its own mesentery. The word volvulus originates from the Latin word volvere, meaning “to twist.” Colonic volvulus is a rare cause of bowel obstruction, collectively accounting for only 2%–3% of cases of colonic obstruction in the United States. Sigmoid volvulus is the most common form and accounts for about two-thirds of cases. Cecal volvulus is present in almost one-third of cases, while volvulus of the transverse colon is extremely rare. During intrauterine development of the fetus, the intestinal tract rotates counterclockwise and is drawn into the peritoneum and out of the yolk sac. The cecum normally fixes to the right retroperitoneum and posterolateral abdominal wall. Incomplete fixation with a mobile cecum puts patients at a risk for cecal volvulus. Other risk factors include previous surgery that may result in adhesions that create a point of fixation for twisting, chronic constipation with colon dilation, intestinal malformations including malrotation, excessive exercise, distal colon obstruction, very high fiber diets, and late pregnancy. The patient in this scenario has a cecal volvulus as demonstrated by her radiograph. She has signs of ischemic bowel based on her physical examination, vitals, and acidotic state. She needs prompt surgical treatment. Mortality increases with both the presence of ischemic bowel and a delay in surgical treatment. Nonsurgical treatment has no role in a patient with evidence of bowel ischemia. Even if this patient was stable without any signs of bowel compromise, endoscopic decompression has been found to be ineffective in the majority of cases of cecal volvulus. A right hemicolectomy should be performed with a complete resection of all ischemic/gangrenous bowel and primary anastomosis if the margins appear healthy and well-perfused bowel. The decision to perform an end ileostomy is based on multiple factors including nutritional status, anemia, use of chronic steroids, other comorbidities, and the appearance of the tissues. In cases where there is no ischemic or gangrenous bowel, detorsion and cecopexy can be considered in the frail or elderly population where minimal surgery is preferred. This is reasonable although recurrence rates are higher. Detorsion and cecostomy tube are no longer performed because the complication and mortality rates are much higher than with cecopexy. Resection should always be performed in the case of ischemic bowel and should be attempted whenever possible, even in the cases of non- ischemic bowel, when the patient can tolerate the operation because it is the definitive treatment and eliminates the risk of recurrence.

Answer 190

ANSWER: D COMMENTS: The prerequisite for the development of sigmoid or cecal volvulus is a mobile segment of bowel that can rotate around a mesentery whose points of fixation are in proximity. Typically, the cecum rotates around the ileocolic artery, while the sigmoid rotates around the IMA. Otherwise, there are surprisingly few similarities between sigmoid and cecal volvulus. Volvulus of the cecum is found most frequently in persons 25 to 35 years of age, whereas it is unusual for sigmoid volvulus to occur in an active, otherwise healthy individual. Usually, it occurs in the elderly, debilitated persons, or those with psychiatric or neurologic disorders in which immobility, medications that impair bowel motility, and loss of accessory defecatory muscles may lead to constipation and elongation of the colon. Both types of volvulus typically cause abdominal distention and pain. With cecal volvulus, plain abdominal films may show evidence of small bowel obstruction and a dilated colon segment extending into the left upper quadrant, whereas with sigmoid volvulus, the distended twisted loop has a fairly characteristic appearance of a “bent inner tube” extending into the right upper quadrant. For sigmoid volvulus, endoscopic detorsion plus insertion of a rectal tube to evacuate the voluminous fecal contents is the preferred initial therapeutic approach but should be attempted only if the mucosa does not appear gangrenous. It should not be attempted if the patient has rebound abdominal tenderness or other signs of peritoneal inflammation. Evidence of gangrenous bowel mandates surgical management. Although nonoperative detorsion is successful approximately 70%–80% of the time, recurrence rates have been reported from 33% to as high as 90%, and therefore an elective resection of the elongated colon is recommended if the patient has an acceptable operative risk. Data from the Veterans Affairs (VA) Hospitals have reported mortality rates as high as 24% for patients undergoing initial emergency operations for sigmoid volvulus versus only 6% for patients initially treated with endoscopic decompression followed by scheduled sigmoid resection soon afterward. Nonoperative colonoscopic reduction of cecal volvulus is difficult and usually ineffective. Prompt surgery is the mainstay of treatment for cecal volvulus. If gangrenous, the cecum must be resected. In the absence of vascular compromise, either resection or sutured cecopexy is a reasonable option. The most important determinant of a patient’s outcome is whether bowel gangrene is present, with mortality being highest if surgery is performed for intestinal infarction or perforation. Mortality is also higher if operating for recurrent volvulus.

Answer 191

ANSWER: C COMMENTS: Sigmoid volvulus is the most common type of volvulus. Cecal volvulus accounts for approximately one-third of cases of colonic volvulus. The causes of cecal volvulus can be congenital or acquired. During embryological development, the cecum normally rotates into the right lower quadrant and becomes fixed to the retroperitoneal structures and right gutter. Incomplete fixation can put patients at a risk for cecal volvulus. Other risk factors include previous surgery (allowing adhesions to create a point of fixation for twisting), chronic constipation, intestinal malformation, excessive exercise, distal colon obstruction, very high fiber diets, and late pregnancy. There are three types of cecal volvulus: Type I: Axial torsion—An axial volvulus from clockwise twisting of the cecum around the axis of the ileocolic artery. The cecum remains in the right lower quadrant. * Type II: Loop torsion—A torsion of the cecum and a portion of the terminal ileum resulting in a displacement of the cecum out of the right lower quadrant into the left upper quadrant. This is the most common type. * Type III: Cecal bascule type—The cecum flows upward into the midepigastrium or left upper quadrant on a tangential fold from the hepatic flexure in the right upper quadrant down toward the left lower quadrant. Surgery is the mainstay of treatment for cecal volvulus. Right hemicolectomy is the procedure of choice since it eliminates the problem. If resection is not desired or the simplest procedure is preferred in a compromised patient, cecopexy by raising a flap of lateral peritoneum and fixing the cecum to the right gutter under this flap may be considered. However, recurrence rates are fairly high. If there is any compromise of the bowel such as gangrene or ischemia, resection is mandatory. In most circumstances, the primary ileocolic anastomosis is safe, although ileostomy and either distal closure or mucous fistula is an option.

Answer 192

ANSWER: C COMMENTS: The colon contains a higher concentration of bacteria, both aerobic and anaerobic, than any other part of the body. Infectious complications constitute the major morbidity of colorectal operations and occur at higher rates than most other general surgery procedures. Escherichia coli is the most common aerobic organism and Bacteroides the most common anaerobic organism found in the colon. Mechanical cleansing of the colon has been a time-honored practice that can be achieved by the administration of a cathartic in combination with enemas or by peroral lavage with a nonabsorbable polyethylene glycol–electrolyte (PEG) solution administered the afternoon before surgery. Although there was a period when mechanical bowel preparation prior to colectomy was felt to be unnecessary, recent data have shown that the combination of mechanical preparation, oral antibiotics, and one preoperative dose of intravenous antibiotics within 30 min of the skin incision is the best approach to reduce colorectal surgical site infections. Oral and rectal Fleet Phospho-Soda (sodium phosphate) was commonly used in the past because of its efficacy in mechanically cleansing the bowel with less volume. However, its use has been associated with significant electrolyte derangements causing compromise of patients with renal insufficiency, cirrhosis, ascites, and congestive heart failure. Therefore it was removed from the market. Polyethylene glycol is not contraindicated in patients with renal failure, cirrhosis, ascites, or congestive heart failure since it generally preserves electrolyte balance. Complete bowel obstruction and bowel perforation are absolute contraindications to mechanical bowel preparation.

Answer 193

ANSWER: E COMMENTS: Diverticulitis is the inflammation caused by perfo- ration of a colonic diverticulum. In many cases, the perforation is microscopic and results in local infection and inflammation in the bowel wall and adjacent mesentery. In complicated diverticulitis, a larger perforation may cause a phlegmon, abscess, fistula, or peritonitis. The severity of complicated acute diverticulitis is graded by the Hinchey classification: * Stage I: Diverticulitis with a localized pericolic or mesocolic abscess * Stage II: Diverticulitis with a pelvic abscess * Stage III: Perforation with purulent peritonitis * Stage IV: Perforation with fecal peritonitis The Hinchey classification does not describe uncomplicated diverticulitis or late complications such as fistula or stenosis. It provides a loose guideline to the management of acute complicated disease. Historically, sigmoid colectomy with diverting colostomy and rectal stump—the Hartmann’s procedure—was the primary treatment for acute diverticulitis. It is still the most common procedure performed in the acute setting. In recent years, primary anastomosis has been found to be reasonable for selected patients presenting with a walled off abscess or localized peritonitis. The anastomosis must be tension free, inflammation free, away from the inflammatory site or abscess cavity, and well vascularized. Tissues to be anastomosed must be healthy and not involved in the inflammatory process. The patient must be stable, and a complete washout should be performed. A number of studies have been performed looking at the option of laparoscopic washout and drainage without resection. Although some surgeons have been enthusiastic, the studies are low powered and general consensus recommendations have not yet shifted to this approach. A recent multicenter, randomized trial from the Scandinavian countries showed that primary resection was superior to laparoscopic lavage. Mortality, quality of life, and hospital stay were not different; however, the reoperation rate was higher and several sigmoid cancers were missed. Still, most cases of diverticulitis are managed nonoperatively with antibiotics. Radiologic drainage of localized abscesses is usually well tolerated. The general plan is for observation of uncomplicated patients. Interval resection is usually reserved for patients with a drained abscess, a fistula, or multiple episodes of diverticulitis. The need for resection after radiologic drain is now being questioned; this is currently being studied.

Answer 194

ANSWER: D COMMENTS: Anastomotic leaks after a colorectal operation can present in a variety of ways, from isolated postoperative tachycardia to fulminant sepsis and peritonitis. Multiple factors have been implicated in the development of anastomotic leak, few of which are definitive. Implicated, or associated but not necessarily causal, are the use of drains, advanced malignancy, shock, malnutrition, emergent surgery, smoking, steroid use, male gender (related to a narrow pelvis), and technical reasons. The gut microbiome has recently been increasingly implicated in the development of leaks, independent of other predictors. Studies are in progress to evaluate this mechanism. Factors that have been definitively related are poor blood supply, tension on the suture line, use of radiated tissue, emergency operations, and contaminated fields. Anastomoses in the low rectum are more technically challenging and therefore at higher risk of a leak. Ileorectal anastomoses have the highest leak rate of any colonic anastomosis, although it is not clear why. Patients with Crohn’s disease have a slightly higher incidence of anastomotic leaks. Extensive research has shown that there is no overall differ- ence in the anastomotic leak rates of hand-sewn and stapled anastomoses. However, a deep pelvic colorectal anastomosis is much easier to construct with a stapler, while a hand-sewn anastomosis should be considered when the bowel is thick, edematous, or otherwise not suitable for stapling.

Answer 195

ANSWER: B COMMENTS: When performed in low-risk patients with attention to good technique, the creation of a Brooke ileostomy is a safe and well-tolerated procedure with few postoperative complications. Originally described by Bryan Brooke in 1952, the everted and primarily matured ileostomy surmounted the problems of serositis, stenosis, and retraction, known as ileostomy dysfunction. The crucial elements of successful ostomy creation include preoperative site marking by a knowledgeable surgeon or enterostomal nurse, adequate mobilization of the mesentery to allow a tension-free ostomy, and primary maturation with eversion using tripartite sutures. Obese patients with a thick abdominal wall and deep skin folds present a challenge since site selection may be difficult and the mesentery may be thick and short. Inadequate maturation and excessive tension from the mesentery can cause retraction, which interferes with effective pouching, leading to wound care difficulties, skin rashes and breakdown, leakage, and occasional soft tissue infections. Finally, a poorly sized fascial aperture can lead to obstruction or ischemia if too small, or a parastomal or prolapse if too large. For these reasons, up to one- third of patients eventually require operative revision or reversal of their ostomy. Peristomal rashes and skin breakdown are usually due to ineffective pouching because of poor patient education or compliance, or due to the ostomy problems such as retraction, prolapse, poor siting, or hernia. The services of a trained enterostomal nurse (WOCN, wound ostomy care nurse) are invaluable. Ideally, patients scheduled for surgery that will include an ostomy will have a preoperative WOCN consultation and organized postoperative training on ostomy care. WOCNs will also allow nonoperative management of many problems. Patients with Crohn’s disease and, rarely, ulcerative colitis may develop pyoderma gangrenosum with serpiginous skin ulcers. Although pyoderma is typically developing in the pretibial skin, it can also develop around a stoma or in a skin incision. If pyoderma is suspected, the patient should be evaluated for Crohn’s disease, if not already diagnosed. Treatment includes medical control of the IBD and local care with various immunosuppressive topical agents and ostomy appliances. Tacrolimus cream has been quite effective in many patients. The Brooke method of maturation refers to folding over the mucosa to hide the serosa, preventing serositis and ileitis. This method does not prevent mucosal sloughing, a complication related to ischemia.

Answer 196

ANSWER: C COMMENTS: Most perirectal abscesses are the result of obstruction of the anal ducts and glands lying in the intersphincteric space. Horseshoe abscesses include bilateral ischiorectal, supra- levator, or perianal abscesses that communicate. Horseshoe abscesses usually arise from infection of the posterior midline glands. A horseshoe ischiorectal abscess starts in the deep postanal space and extends bilaterally into each ischiorectal space. The patient is best treated in the operating room under regional or general anesthesia by incising the skin from the external sphincter to the coccyx. This exposes the superficial external sphincter, which is split longitudinally but not transected. The incision provides access to the deep postanal space. A probe is inserted into the posterior midline crypt and then into the deep postanal space. A seton is placed in this space and wrapped around the internal sphincter and superficial external sphincter. Counterincisions are made laterally along extensions of the abscess. An intersphincteric abscess is usually accompanied by pain and bulging inside the rectum but no external swelling. Treatment consists of transanally laying open the internal sphincter, beginning at the lower edge of the abscess and extending cephalad to the top of the abscess cavity. Most perianal abscesses can be drained with the use of local anesthesia, but if the patient has a high fever, significant leukocytosis, or extreme pain, treatment in the operating room under general anesthesia is preferable. Identification of a fistula may be deferred until there are clinical signs that a fistula is present, specifically, nonhealing of an abscess wound or recurrence of the abscess at the same location. Patients with anorectal Crohn’s disease may experience recurrent abscesses despite maximal therapy. Anorectal abscesses may be the first manifestation of Crohn’s disease in over 5% of patients, and up to 50% of patients with Crohn’s disease will develop anorectal issues including abscesses, fistulas, anal ulcers, and large swollen skin tags at some point in their disease process.

Answer 197

ANSWER: E COMMENTS: Endorectal ultrasound imaging has had a signifi- cant impact on the diagnosis and management of a variety of anorectal diseases. The initial use of endoluminal ultrasound was for the staging of rectal cancers. The depth of penetration and the presence of abnormal lymph nodes were used to determine the stage of the cancer and its suitability for local excision. Generally, tumors that demonstrate deep penetration of the rectal wall have an increased likelihood of lymph node metastases and are not suitable candidates for transanal excision because of the unacceptably high recurrence rates associated with local excision of these advanced neoplasms. Most surgeons would restrict transanal excision to T1 tumors for curative intent. Recently, the use of ultra- sound imaging for staging rectal cancers has been expanded to determine whether a lesion is advanced enough to warrant preop- erative radiation therapy and chemotherapy. Ultrasound imaging can be used to assess the rectal wall and the extraluminal tissue for any sign of recurrent cancer following surgery. In this respect, it has distinct advantages over other imaging modalities, such as computed tomography, in that the probe is placed in direct contact with the operative site. Ultrasound has never been demonstrated to be beneficial for routine screening for rectal cancer. Ultrasound requires the application of the probe directly to the tissue of interest. Endoscopic ultrasound (EUS) may be useful in several benign diseases of the anus and rectum. It may be used to image the sphincter mechanism in patients complaining of fecal incontinence. In fact, before a diagnosis of idiopathic or neurogenic incontinence is made, an ultrasound scan should be done to inspect the integrity of the sphincter. Ultrasound provides excellent diagnostic accuracy in determining disruptions of the internal and/or external sphincters. Although most anorectal abscesses and fistulas can be managed without imaging studies, ultrasound has proved useful for deter- mining the extent of abscess collections laterally and in a cephalad direction. Furthermore, the relation of the tract of the fistula to the sphincter muscle can be assessed with ultrasound imaging. The internal opening can be identified as a hypoechoic disruption of the internal sphincter muscle. Hydrogen peroxide may be injected into the fistula tract during ultrasound scanning to further delineate the fistula tract.

Answer 198

ANSWER: E COMMENTS: Internal hemorrhoids are submucosal cushions normally located above the dentate line and are therefore covered by the transitional mucosa of the anal canal and not by anoderm. External hemorrhoids are the dilated veins of the inferior hemor- rhoidal plexus located below the dentate line and are covered by anoderm. Prolapsing hemorrhoids are internal hemorrhoids that prolapse below the dentate line. Bleeding is the main manifestation of smaller internal hemorrhoids and is managed initially by rubber banding, infrared coagulation, or injection sclerotherapy. Surgery is reserved for internal hemorrhoids that do not respond to dietary measures and office procedures. Surgery may be the best initial therapy for large prolapsing internal hemorrhoids or for those that are acutely thrombosed and incarcerated. Thrombosed external hemorrhoids are most often treated by excision using local anesthesia in the office setting. General anesthesia is only required in the uncommon situation when they are quite large and circumferential. Internal hemorrhoidal recurrence is rare after formal surgical hemorrhoidectomy. When it does occur, it is usually related to inadequate removal of the rectal mucosa and hemorrhoidal tissue or inadequate management of chronic constipation.

Answer 199

ANSWER: E COMMENTS: An anal fissure is a tear of the skin-lined portion of the anal canal located below the dentate line. It is most commonly caused by hard bowel movements and straining. Occasionally, high internal anal sphincter tone is the cause. Gentle spreading of the buttocks is frequently all that is needed to reveal the fissure. Once the acute fissure is identified, digital examination and anoscopy may be deferred in the acute setting. About 90% of fissures (acute or chronic) are located in the posterior midline, an area where the anoderm is least supported by the sphincter and where blood flow is the poorest. The anterior midline is the second most common location and is involved in 10% of women. Fissures located laterally or multiple fissures should arouse suspicion for Crohn’s disease, syphilis, tuberculosis, leukemia, or other causes, and therapy is directed toward the underlying disease. The initial treatment of a midline fissure is conservative and starts with a bowel management program including lubricants, fluids and fiber supplements, and warm baths. Over 90% of acute fissures will heal with this approach. Topical nitroglycerin or calcium channel blocking agents may help resolve chronic fissures in approximately 50% of patients; however, several weeks or months of treatment may be required. Botox injected directly into the internal sphincter on either side of the fissure may also produce healing in approximately 60% of patients. However, recurrence is common. Persistent chronic fissures are often used to high internal anal sphincter tension, which can be demonstrated on digital rectal examination or by anorectal manometry. Operative treatment consists of lateral partial internal sphincterotomy up to the dentate line to relax the internal sphincter. Posterior fissurectomy and sphincterotomy can lead to a keyhole defect and soiling. For this reason, lateral internal sphincterotomy has become the procedure of choice. Although mild incontinence to gas or diarrhea may be seen, it is infrequent enough to justify sphincterotomy in the small number of patients who do not respond to conservative therapies. External sphincterotomy should not be performed for anal fissure because it is not necessary and leads to unacceptably high rates of incontinence.

Answer 200

ANSWER: C COMMENTS: Precursors to malignant disease are often found in the anal margin. Anal intraepithelial neoplasias, such as Bowen’s or Paget’s disease, can cause symptoms such as itching. Skin changes are usually present, and biopsy is indicated whenever the pruritus does not resolve with conservative measures. Bowen’s disease represents high-grade dysplasia or squamous cell carcinoma in situ of the perianal skin. It is often associated with the human papillomavirus (HPV) (especially HPV types 16 and 18). It is usually indolent, and less than 5% progress to invasive cancer. Treatment consists of wide local excision with clear margins. Paget’s disease is adenocarcinoma in situ of the perianal skin, usually from skin appendages such as ducts and glands. A lower gastrointestinal malignancy, usually a rectal or anal carcinoma, is found in 50%–70% of patients, but it is not associated with breast cancer. After evaluating the colon and anorectum for synchronous tumors, treatment is wide local excision. This disease may be multicentric, so circumferential mapping biopsies around the anal canal and perineum are part of the procedure. With HPV-related neoplasia, high-resolution anoscopy may be useful for targeting biopsies with excision or destruction of abnormal tissue, but this is primarily used in human immunodeficiency virus (HIV)–positive patients and men who have anoreceptive intercourse. Basal cell carcinoma of the perianal skin is rare and is associated with a 5-year survival rate of almost 100% following local surgical excision. Buschke- Löwenstein tumors, also called giant condylomas, are large verrucous squamous cell tumors of the anal canal and perineum due to HPV infection. Pathologically, they resemble condyloma and may have areas of invasive squamous cell carcinoma. They are rarely metastatic but may invade local structures around the anal canal or margin. Treatment consists of wide local excision or, rarely, abdominoperineal resection (APR) if the sphincter is invaded. Radiation therapy is occasionally used preoperatively to shrink large cancers or for patients with recurrent tumors.

Answer 201

ANSWER: A COMMENTS: Anal infection with HPV is responsible for condyloma acuminatum, which appears as a group of cauliflower-shaped masses on the perianal skin and in the anal canal. The disease is transmitted by close contact and is seen in both genders regardless of whether anal intercourse is practiced. It is especially prevalent in anoreceptive men who have sex with men, and in this population, it is seen more often than genital warts. Another high-risk population consists of those receiving immunosuppression after organ transplantation. Podophyllin, a cytotoxic agent available in 10% and 25% solutions, must be applied by a physician. However, the results have been disappointing. Clearance of the warts has been noted in 22%–77% of patients, with recurrence rates being as high as 65%. Podophyllin may cause skin burns and cannot be used within the anal canal. Multiple treatments are usually necessary. Failure to treat intraanal lesions results in persistent disease. An autologous vaccine prepared from sampled condyloma can be injected weekly for 6 weeks. No adverse reactions have been seen, and resolution of lesions has been noted in up to 95% of patients. However, the process is not standardized, and so at present, such therapy is only considered for extensive, persistent, or recurrent cases of condyloma. Malignant transformation is a concern but occurs only rarely. Surgical treatment includes excision by one of three techniques (sharp excision with scissors, laser vaporization, or electrocautery excision and fulguration). Electrocautery is the preferred therapy and is associated with a recurrence rate of 10%– 25%. With close follow-up and treatment of any recurrence, 95% of patients are rendered disease free. There is a risk of surgeon infection within the respiratory tract from the inhalation of vaporized viral particles. This risk can be minimized by using smoke evacuators and special masks during procedures.

Answer 202

ANSWER: D COMMENTS: Rectovaginal fistulas are classified according to location and cause, which influences the type of corrective surgery required. High fistulas require an abdominal approach, whereas low fistulas can be repaired through a transanal, transperineal, or transvaginal approach. The common causes of these fistulas include obstetrical injuries, primary or recurrent cancer, radiation treatment of pelvic cancers, inflammatory bowel disease, trauma, or infection (e.g., cryptoglandular infection, tuberculosis, or lymphogranuloma venereum). Five percent of all vaginal deliveries are accompanied by third- or fourth-degree perineal lacerations. Approximately 10% of these repairs become disrupted and result in incontinence and/or a rectovaginal fistula. Approximately 50% of these obstetric fistulas heal spontaneously (not 85%); therefore if the patient’s symptoms are not disabling, a 3- to 6-month waiting period is recommended. This waiting period also allows the tissue inflammation and edema to subside before surgical intervention. Repair of a fistula secondary to an obstetric injury can be performed transvaginally or transrectally. With the former, the tract is excised and the rectovaginal septum is inverted with serial purse-string sutures. With the latter, a flap consisting of mucosa, submucosa, and muscularis is advanced to cover the rectal side of the fistula. A diverting colostomy is not required unless previous surgical attempts have failed. A low ano-vaginal fistula may be treated by fistulotomy, but rectovaginal fistulas (even distal ones) should not be treated by this method. Partial or total incontinence may result if the fistula tract is divided. High rectovaginal fistulas are best treated through a transabdominal approach so that coexisting pathologic conditions such as diverticulitis, cancer, or inflammatory bowel disease can be addressed. The rectovaginal septum is mobilized, the fistula is divided, the vagina is closed, and normal tissue (such as omentum or a muscle flap) is used to buttress the repair. Because the colon is not usually normal (inflammation or radiation injury), bowel resection is generally necessary. Fistulas secondary to Crohn’s disease do not always require proctectomy if the symptoms are minimal, the rectum is relatively healthy, and continence is normal. In such cases, an advancement flap can lead to healing. When there is refractory rectal Crohn’s disease (especially the stricturing form) or incontinence, proctectomy with a colostomy is often ultimately needed. Radiation- induced fistulas may be very difficult to treat since the radiated tissue does not heal well. Repair requires use of nonradiated tissue, and so may include partial proctectomy with left colon-to- rectum anastomosis and/or use of an omental or gracilis muscle flap. A colostomy or ileostomy as sole therapy (e.g., a poor-risk patient with recurrent, unresectable cancer or multiple failed attempts at repair) or to divert stool from an anastomosis after resection of diseased bowel is often necessary.

Answer 203

ANSWER: B COMMENTS: Fecal incontinence is commonly related to obstetric injuries, which result in a sphincter defect. However, the quality of the stool is also a common contributing cause of incontinence. A patient with marginal sphincter function may experience incontinence when the stool is loose or watery. Treatment with bulk- forming agents, such as psyllium husk, and/or loperamide will bulk the stool. Treatment of the diarrhea will cure the symptoms of incontinence in many patients. If unsuccessful, then physical therapy including biofeedback may be employed. Sphincter reconstruction and sacral nerve stimulation are well documented to improve symptoms; however, they should be reserved for patients who do not improve with medical therapy and bowel management.

Answer 204

ANSWER: C COMMENTS: This is a localized anal canal squamous cell carcinoma. TNM staging of anal carcinoma includes the size of the primary lesion. T1 lesions are 2 cm or less in diameter; T2 are > 2 cm to 5 cm, T3 are > 5 cm, and T4 are invading into an adjacent structure beyond the sphincter muscles. The lesion is staged as T2, N0, M0. Endorectal ultrasound or magnetic resonance imaging (MRI) may further define the depth of penetration, extension to other organs, and lymph node status. It is important to examine the inguinal lymph nodes since this is a common site of spread. The primary treatment of localized squamous cell carcinoma of the anal canal was defined by Norman Nigro, M.D. (the Nigro protocol), who demonstrated that combined chemoradiation therapy was much more effective than radical surgery (APR), with high rates of anal preservation. The modified Nigro protocol in use today includes a course of chemotherapy using 5-fluorouracil (5-FU) and mitomycin C and 6 weeks of radiation therapy to a dose of about 5400 cGy. Anal canal carcinoma must be differentiated from anal margin carcinoma. Any squamous cell carcinoma that has any part within the anal canal (from the anal verge to the anorectal ring) is considered an anal canal carcinoma, while anal margin lesions are entirely outside of the anal canal in the perineal skin. Anal margin carcinomas are treated by local excision with clear margins, which results in a high rate of cure. APR is reserved for persistent or recurrent cancer or if the patient has previously received radiation therapy for other indications. The modified Nigro protocol results in an initial complete response in 90% of patients. Salvage APR for persistence or recurrence results in a cure rate of 25%–50%. So, the overall 5-year disease-free survival for anal canal carcinoma is about 80%.

Answer 205

ANSWER: A COMMENTS: The most common early postoperative complication after hemorrhoid surgery is urinary retention. This typically occurs in 10% (2%–36%) of patients. The incidence of postoperative urinary retention is more common in men and is directly related to the volume of intravenous fluids administered. In addition, it may be related to narcotic administration and regional anesthesia. Other complications include bleeding (0.03%–6%), anal stenosis (0%–6%), infection (0.5%–5%), and incontinence (2%–12%). Bleeding is the next most common complication of stapled hemorrhoidopexy. Other complications unique to stapled hemorrhoidopexy include rectovaginal fistula, rectal perforation, rectal occlusion, and chronic pain related to an inappropriately distal staple line.

Answer 206

ANSWER: D COMMENTS: Rubber band ligation is commonly performed for first- and second-degree hemorrhoids. The band is placed on the redundant mucosa a minimum of 2 cm proximal to the dentate line. This will slough off in 5-7 days and can be associated with light bleeding. Complications of banding include pain, thrombosis, bleeding, and perineal or pelvic sepsis. Placing the band too close to the dentate line will cause immediate pain and require removal. Thrombosis of the internal, external, or both complexes may be managed by observation and analgesics if mild or by operative hemorrhoidectomy if extensive. Significant bleeding is abnormal and may require control of the bleeding site in the office or the operating room (OR). Life-threatening sepsis due to necrotizing infection is rare but mandates immediate evaluation and treatment (fluid, antibiotics, and examination in the OR). This sepsis is associated with severe diabetes and states of immune suppression. Early recognition of this problem is critical, and treatment must be rapid.

Answer 207

ANSWER: B COMMENTS: Lymphatic drainage of the upper and middle rectum includes the inferior mesenteric and para-aortic nodes. Drainage from the lower one-third of the rectum occurs partially in a cephalad direction toward the inferior mesenteric artery, but also laterally along the middle hemorrhoidal vessels to the internal iliac nodes. Anal canal lymphatic drainage is defined by the relationship of the lesion to the dentate line. Superior to the dentate line, drainage occurs to the inferior mesenteric and internal iliac nodes. Distal to or below the dentate line, drainage occurs along the inferior lymphatics to the superficial inguinal nodes. The Sister Mary Joseph node is a periumbilical nodule and often due to metastatic gastric or pancreatic cancer.

Answer 208

ANSWER: E COMMENTS: Chronic anal fissures in the lateral position are rare and should prompt consideration of alternative diagnoses. These include Crohn’s disease, leukemia, tuberculosis, syphilis, HIV, or anal carcinoma. The QuantiFERON gold test is useful for diagnosing both active and latent Mycobacterium tuberculosis infection. Medical treatments such as bowel management, Sitz baths, topical lidocaine, topical nitroglycerin, or nifedipine may be initiated for pain relief and to promote healing. However, sphincterotomy should not be recommended until other causative disorders are identified and treated. Sphincterotomy in the setting of untreated Crohn’s disease or HIV may result in nonhealing wounds and/or fecal incontinence.

Answer 209

ANSWER: B COMMENTS: Full-thickness rectal prolapse involves all layers of the rectal wall. It is often associated with fecal incontinence, particularly in elderly multiparous patients. Initial treatment includes high-fiber diet and stool softeners to prevent straining. This may reduce the severity of the prolapse but will not cure it. In healthy patients with constipation, sigmoid resection with sutured rectopexy (Frykman procedure) can result in low rates of recurrence and improvement in constipation. Patients with fecal incontinence ideally should not undergo sigmoid resection, as this may worsen this symptom. Abdominal procedures should be avoided in older frail patients because of the risks. These patients are better suited for a perineal approach such as a perineal rectosigmoidectomy (Altemeier procedure). This is a low-risk operation that may be performed under regional anesthesia or even sedation with local anesthesia. The redundant rectum and colon are resected from the perineal approach with a coloanal anastomosis. A levateroplasty may be added to tighten up the levator hiatus and possibly improve incontinence. Although the loss of the rectal vault may worsen incontinence and frequency and the recurrence rate is higher than with abdominal procedures, the very low risk and rapid recovery make this the best operation in this group of patients.

Answer 210

ANSWER: C COMMENTS: The supralevator space is bounded superiorly by the peritoneum, laterally by the pelvic walls, medially by the rectum, and inferiorly by the levator ani muscles (Figs. 23B.1 and 23B.2). It communicates with the contralateral side posteriorly. Infection in this space can arise from an abdominal or pelvic source (e.g., diverticulitis or pelvic inflammatory disease) or as an upward extension from an anorectal source. The retrorectal space lies above the rectosacral fascia between the upper two-thirds of the rectum and sacrum. The fascia runs downward and forward from the sacrum to the anorectal junction. The retrorectal space contains loose connective tissue and is a site for the formation of tumors arising from embryologic remnants (i.e., dermoids, teratomas, and chordomas). The retrorectal space is bounded anteriorly by the rectum, posteriorly by the presacral fascia, laterally by the pelvic side wall, superiorly by the peritoneal reflection, and inferiorly by the rectosacral fascia, below which is the supralevator space. The ischiorectal space lies below the levator muscle, above the transverse septum of the ischiorectal fossa, and between the external sphincter and the lateral pelvic wall. This space communicates posteriorly through the deep postanal space, which lies between the levator ani and the superficial external sphincter. The lower border of the deep postanal space is the anococcygeal ligament, which originates from the superficial portion of the external sphincter in the posterior midline. This communication allows an abscess in the deep postanal space to extend to both ischiorectal spaces (horse- shoe abscess). The perianal space (the most common space involved in abscesses) lies superficial to the superficial external anal sphincter. The intersphincteric space lies within the conjoined longitudinal muscle, where the anal glands are also located. The perianal, ischiorectal, and supralevator spaces may connect posteriorly with their counterparts on the contralateral side to form a horseshoe connection in any of these spaces.

Answer 211

ANSWER: B COMMENTS: The internal anal sphincter represents the distal 2.5 to 4.0 cm of the circular muscle layer (muscularis propria) of the rectum. This sphincter is therefore smooth muscle and under autonomic control. In its basal state, it is contracted, creating a natural barrier to the loss of stool and gas. The external anal sphincter is a continuation of the puborectalis muscle. This sphincter is a striated muscle, and like the other pelvic floor muscles, it is maintained by an unconscious resting tone at the level of the cauda equine but can be voluntarily relaxed and contracted. The conjoined longitudinal muscle combines with fibers of the levator ani and then descends and crosses the external anal sphincter to insert into the perianal skin.

Answer 212

ANSWER: B COMMENTS: The internal hemorrhoidal tissues originate proximal to the dentate line and are vascular structures that are covered by mucosa (transitional and columnar epithelium). The anal canal from 1 to 2 cm above the dentate line is viscerally innervated and is insensitive to pain, touch, or temperature, and therefore amenable to office procedures without the need for anesthetics. Internal hemorrhoids are classified by 4 degrees depending on the amount of prolapse. Table 23B.1 reviews the differences in internal hemorrhoids by degree.

Answer 213

ANSWER: D COMMENTS: This patient suffers from pilonidal disease. This is mostly likely due to hair follicles that become distended with keratin and then subsequently infected, rupturing into the subcutaneous tissue. This is most likely due to micro-trauma related to the weight of the buttocks having its greatest support (and effect) at the midline skin of the gluteal cleft. The patient does not have an abscess or cellulitis. Therefore drainage or antibiotics are not indicated. Pilonidal disease will cause recurrent symptoms unless definitively treated with excision closure of the midline pit(s) and elimination of the associated epithelialized sinus tract extending from the pit to the abscess cavity. This may be accomplished by excision removing the midline pit, epithelialized tract, and abscess cavity. Excision may be accompanied by leaving the wound open. This is an acceptable treatment option; however, it requires dressing changes that are difficult for patients to perform themselves. The cleft lift procedure has been demonstrated to achieve high rates of cure, with few wound complications; however, as the initial procedure for uncomplicated disease is not indicated, it may be overly aggressive. As the pilonidal is not infected, incision and drainage is not indicated. Simple excision and closure of the wound is indicated. Off-midline closure has been established as the preferred technique compared with midline closure, as this reduces the tension on the wound caused by the weight of the buttocks.

Answer 214

Answer: C The wall of the colon and rectum are made of five separate layers: mucosa, submucosa, circular muscle layer, longitudinal muscle layer, and serosa. The mid and lower rectum lack serosa so this layer would not be stapled through if the surgeon were stapling through the mid or lower rectum. (See Schwartz 10th ed., p. 1176.)

Answer 215

Answer:A The inner circular muscle joins to form the internal anal sphincter. The subcutaneous, superficial, and deep external sphincter surrounds it. The deep external anal sphincter is an extension of the puborectalis muscle. (See Schwartz 10th ed., p. 1176.)

Answer 216

Answer: C The inferior mesenteric vein does not run with the inferior mesenteric artery. Instead, it travels cranially in the retroperitoneum over the psoas and then posterior to the pancreas to join the splenic vein. The vein is often ligated at the inferior edge of the pancreas during a colectomy. (See Schwartz 10th ed., p. 1177.)

Answer 217

Answer: A The presacral fascia separates the rectum from the presacral venous plexus and the pelvic nerves. The rectosacral fascia (Waldeyer fascia) extends forward and downward and attaches to the fascia propria at the anorectal junction. Anteriorly, Denonvilliers fascia separates the rectum from the prostate and seminal vesicles in men and from the vagina in women. (See Schwartz 10th ed., p. 1177.)

Answer 218

Answer: D During the 6th week of gestation, the midgut herniates out of the abdominal cavity and rotates 270° counterclockwise around the superior mesenteric artery and travels to its resting position in the 10th week of gestation. Failure of the mid-gut to rotate and return to the abdominal cavity during the 10th week of gestation results in intestinal malrotation. (See Schwartz 10th ed., pp. 1175, 1179.)

Answer 219

Answer: A Short-chain fatty acids (acetic acid, butyric acid, and propionic acid) are produced by bacterial fermentation of dietary carbohydrates and are an important source of energy for the colonic mucosa, and metabolism by colonocytes provides energy for processes such as active transport of sodium. Diversion of feces by an ileostomy or colostomy can result in “diversion colitis” which is associated with mucosal atrophy and inflammation. (See Schwartz 10th ed., p. 1179.)

Answer 220

Answer: A Defecation proceeds by coordination of increasing intra-abdominal pressure via the Valsalva maneuver, increased rectal contraction, relaxation of the puborectalis muscle, and opening of the anal canal. Impaired continence may result from poor rectal compliance, injury to the internal and/or external sphincter or puborectalis, or nerve damage or neuropathy. (See Schwartz 10th ed., p. 1180.)

Answer 221

Answer: B Fecal occult blood test (FOBT) has been a nonspecific test for peroxidase contained in hemoglobin; consequently, occult bleeding from any gastrointestinal source will produce a positive result. Similarly, many foods (red meat, some fruits and vegetables, and vitamin C) will produce a false-positive result. Any positive FOB mandates further investigation, usually by colonoscopy. (See Schwartz 10th ed., p. 1182.)

Answer 222

Answer: D Stool wet-mount and culture can often diagnose infection. Sigmoidoscopy or colonoscopy can be helpful in diagnosing inflammatory bowel disease for ischemia. However, if the patient has abdominal tenderness, particularly with peritoneal signs, or any other evidence of perforation, endoscopy is contraindicated. For chronic diarrhea, tests for malabsorption and metabolic investigations should be conducted along with colonoscopy. Biopsies should be taken even if the colonic mucosa appears grossly normal. (See Schwartz 10th ed., p. 1184.)

Answer 223

Answer: A In an emergency operation, like this one, where the stoma site has not been marked, an attempt should be made to place a stoma within the rectus muscle and away from both the costal margin and iliac crest. In emergencies, placement high on the abdominal wall is preferred to a low-lying site. (See Schwartz 10th ed., p. 1192.)

Answer 224

Answer: C A flexible endoscopic examination and a contrast enema (Gastrografin) are recommended prior to closure to ensure that the anastomosis has not leaked and is patent. (See Schwartz 10th ed., p. 1193.)

Answer 225

Answer: C Stoma necrosis may occur in the early postoperative period and is usually caused by skeletonizing the distal small bowel and/or creating an overly tight fascial defect. Limited mucosal necrosis above the fascia may be treated expectantly, but necrosis below the level of the fascia requires surgical revision. Stoma retraction may occur early or late and may be exacerbated by obesity. Local revision may be necessary. (See Schwartz 10th ed., p. 1193.)

Answer 226

Answer: E The functional outcome of ileal pouch-anal reconstruction is not always perfect. Patients should be counseled to expect 8 to 10 bowel movements per day. Up to 50% have some degree of nocturnal incontinence. Pouchitis occurs in nearly 50% of patients who undergo the operation or chronic ulcerative colitis, and small bowel obstruction is common. Pouches fail in 5 to 10% of patients.

Answer 227

Answer: B This patient is likely presenting with pouchitis. Pouchitis is an inflammatory condition that affects both ileoanal pouches and continent ileostomy reservoirs. The incidence of pouchitis ranges from 30 to 55%. Symptoms include increased diarrhea, hematochezia, abdominal pain, fever, and malaise. Diagnosis is made endoscopically with biopsies. Differential diagnosis includes infection and undiagnosed Crohn disease. (See Schwartz 10th ed., p. 1194.)

Answer 228

Answer: C Prospective randomized trials are needed to better understand the role of oral antibiotic prophylaxis in colorectal surgery. In contrast, long-standing, convincing data support the efficacy of parenteral antibiotic prophylaxis at the time of surgery. Broad-spectrum parenteral antibiotic(s) with activity against aerobic and anaerobic enteric pathogens should be administered just prior to the skin incision and redosed as needed depending on the length of the operation. There is no proven benefit to using antibiotics postoperatively after an uncomplicated colectomy.

Answer 229

Answer: C Family history may play a role in inflammatory bowel disease as 10 to 30% of patients within inflammatory bowel disease report a family member with the same disease. (See Schwartz 10th., p. 1195.)

Answer 230

Answer: B Ulcerative colitis is a mucosal process in which the colonic mucosa and submucosa are infiltrated with inflammatory cells. The mucosa may be atrophic, and crypt abscesses are common. Endoscopically, the mucosa is requently friable and may possess multiple inflammatory pseudopolyps. In long-standing ulcerative colitis, the colon may be foreshortened and the mucosa replaced by scar. A key feature of ulcerative colitis is the continuous involvement of the rectum and colon; rectal sparing or skip lesions suggest a diagnosis of Crohn disease. Crohn disease is a transmural inflammatory process that can affect any part of the gastrointestinal tract from mouth to anus. Mucosal ulcerations, an inflammatory cell infiltrate, and noncaseating granulomas are characteristic pathologic findings. Chronic inflammation may ultimately result in fibrosis, strictures, and fistulas in either the colon or small intestine. The endoscopic appearance of Crohn colitis is characterized by deep serpiginous ulcers and a “cobblestone” appearance. (See Schwartz 10th ed., p. 1195.)

Answer 231

Answer: A The liver is a common site of extracolonic disease in inflammatory bowel disease. Fatty infiltration of the liver is present in 40 to 50% of patients, and cirrhosis is found in 2 to 5%. Primary sclerosing cholangitis is a progressive disease characterized by intra- and extrahepatic bile duct strictures. Forty to 60% of patients with primary sclerosing cholangitis have ulcerative colitis. Pericholangitis is also associated with inflammatory bowel disease and may be diagnosed with a liver biopsy. Bile duct carcinoma is a rare complication of long-standing inflammatory bowel disease. Arthritis also is a common extracolonic manifestation of inflammatory bowel disease, and the incidence is 20 times greater than in the general population. Erythema nodosum is seen in 5 to 15% of patients with inflammatory bowel disease and usually coincides with clinical disease activity. Pyoderma gangrenosum is an uncommon but serious condition that occurs almost exclusively in patients with inflammatory bowel disease. Up to 10% of patients with inflammatory bowel disease will develop ocular lesions. These include uveitis, iritis, episcleritis, and conjunctivitis. (See Schwartz 10th ed., p. 1196.)

Answer 232

Answer:A Ulcerative colitis is a mucosal process in which the colonic mucosa and submucosa are infiltrated with inflammatory cells. The mucosa may be atrophic, and crypt abscesses are common. Endoscopically, the mucosa is frequently friable and may possess multiple inflammatory pseudopolyps. In long- standing ulcerative colitis, the colon may be foreshortened and the mucosa replaced by scar. A key feature of ulcerative colitis is the continuous involvement of the rectum and colon; rectal sparing or skip lesions suggest a diagnosis of Crohn disease. Crohn disease is a transmural inflammatory process that can affect any part of the gastrointestinal tract rom mouth to anus. Mucosal ulcerations, an inflammatory cell infiltrate, and noncaseating granulomas are characteristic pathologic findings. Chronic inflammation may ultimately result in fibrosis, strictures, and fistulas in either the colon or small intestine. The endoscopic appearance of Crohn colitis is characterized by deep serpiginous ulcers and a “cobblestone” appearance. (See Schwartz 10th ed., p. 1195.)

Answer 233

Answer: A Sulfasalazine (Azulfidine), 5-acetyl salicylic acid (5-ASA), and related compounds are first-line agents in the medical treatment of mild to moderate inflammatory bowel disease. These compounds decrease inflammation by inhibition of cyclooxygenase and 5-lipoxygenase in the gut mucosa. They require direct contact with affected mucosa for efficacy. Multiple preparations are available for administration to different sites in the small intestine and colon. Antibiotics are often used to decrease the intraluminal bacterial load in Crohn disease. Metronidazole has been reported to improve Crohn colitis and perianal disease, but the evidence is weak. Fluoroquinolones may also be effective in some cases. In the absence of fulminant colitis or toxic megacolon, antibiotics are not used to treat ulcerative colitis. Corticosteroids (either oral or parenteral) are a key component of treatment for an acute exacerbation of either ulcerative colitis or Crohn disease. Corticosteroids are nonspecific inhibitors of the immune system, and 75 to 90% of patients will improve with the administration of these drugs. Azathioprine and 6-mercatopurine (6-MP) are antimetabolite drugs that interfere with nucleic acid synthesis and thus decrease proliferation of inflammatory cells. These agents are useful for treating ulcerative colitis and Crohn disease in patients who have failed salicylate therapy or who are dependent on, or refractory to, corticosteroids. (See Schwartz 10th ed., p. 1196.)

Answer 234

Answer: B Patients with inflammatory bowel disease are often malnourished. Abdominal pain and obstructive symptoms may decrease oral intake. Diarrhea can cause significant protein loss. Ongoing inflammation produces a catabolic physiologic state. Parenteral nutrition should be strongly considered early in the course of therapy or either Crohn disease or ulcerative colitis. The nutritional status of the patient also should be considered when planning operative intervention, and nutritional parameters such as serum albumin, prealbumin, and transferrin should be assessed. In extremely malnourished patients, especially those who are also being treated with corticosteroids, creation of a stoma is often safer than a primary anastomosis. (See Schwartz 10th ed., p. 1197.)

Answer 235

Answer: E Emergency surgery is required for patients with massive life- threatening hemorrhage, toxic megacolon, or fulminant colitis who fail to respond rapidly to medical therapy. Patients with signs and symptoms of fulminant colitis should be treated aggressively with bowel rest, hydration, broad-spectrum antibiotics, and parenteral corticosteroids. Colonoscopy and barium enema are contraindicated, and antidiarrheal agents should be avoided. Deterioration in clinical condition or failure to improve within 24 to 48 hours mandates surgery. (See Schwartz 10th ed., p. 1197.)

Answer 236

Answer: A The most common indications for surgery are internal fistula or abscess (30–38% of patients) and obstruction (35–37% of patients). Crohn disease of the large intestine may present as fulminant colitis or toxic megacolon. In this setting, treatment is identical to treatment of fulminant colitis and toxic megacolon secondary to ulcerative colitis. Resuscitation and medical therapy with bowel rest, broad-spectrum antibiotics, and parenteral corticosteroids should be instituted. If the patient’s condition worsens or fails to rapidly improve, total abdominal colectomy with end ileostomy is recommended. (See Schwartz 10th ed., p. 1199.)

Answer 237

Answer: A The most common perianal lesions in Crohn disease are skin tags that are minimally symptomatic. Fissures are also common. Typically, a fissure from Crohn disease is particularly deep or broad and perhaps better described as an anal ulcer. These fissures are often multiple and located in a lateral position rather than anterior or posterior midline as seen in an idiopathic fissure-in-ano. A classic-appearing fissure in ano located laterally should raise the suspicion of Crohn disease. (See Schwartz 10th ed., p. 1200.)

Answer 238

Answer: D The majority of colonic diverticula are false diverticula in which the mucosa and muscularis mucosa have herniated through the colonic wall. These diverticula occur between the teniae coli, at points where the main blood vessels penetrate the colonic wall (presumably creating an area of relative weakness in the colonic muscle). They are thought to be pulsion diverticula resulting from high intraluminal pressure. The most accepted theory is that a lack of dietary fiber results in smaller stool volume, requiring high intraluminal pressure and high colonic wall tension or propulsion. Chronic contraction then results in muscular hypertrophy and develop- ment of the process of segmentation in which the colon acts like separate segments instead of functioning as a continuous tube. As segmentation progresses, the high pressures are directed radially toward the colon wall rather than to development of propulsive waves that move stool distally. The high radial pressures directed against the bowel wall create pulsion diverticula. (See Schwartz 10th ed., p. 1201.)

Answer 239

Answer: B Many surgeons now will not advise colectomy even after two documented episodes of diverticulitis assuming the patient is completely asymptomatic and that carcinoma has been excluded by colonoscopy. Immunosuppressed patients are generally still advised to undergo colectomy after a single episode of documented diverticulitis. Medical comorbidities should be considered when evaluating a patient for elective resection, and the risks of recurrent disease should be weighed against the risks o the operation. Because colon carcinoma may present in an identical fashion to diverticulitis (either complicated or uncomplicated), all patients must be evaluated for malignancy after resolution of the acute episode. Colonoscopy is recommended 4 to 6 weeks after recovery. Inability to exclude malignancy is another indication for resection. (See Schwartz 10th ed., p. 1202.)

Answer 240

Answer: A* The Hinchey staging system is often used to describe the severity of complicated diverticulitis: Stage I includes colonic inflammation with an associated pericolic abscess; stage II includes colonic inflammation with a retroperitoneal or pelvic abscess; stage III is associated with purulent peritonitis; and stage IV is associated with fecal peritonitis. (See Schwartz 10th ed., p. 1202.)

Answer 241

Answer: D Approximately 5% of patients with complicated diverticulitis develop fistulas between the colon and an adjacent organ. Colovesical fistulas are most common, followed by colovaginal and coloenteric fistulas. Colocutaneous fistulas are a rare complication of diverticulitis. (See Schwartz 10th ed., p. 1203.)

Answer 242

Answer: A Mutations may cause activation of oncogenes (K-ras) and/or inactivation of tumor suppressor genes (APC, deleted in colorectal carcinoma [DCC], p53). Colorectal carcinoma is thought to develop from adenomatous polyps by accumulation of these mutations in what has come to be known as the adenoma-carcinoma sequence. The APC gene is a tumor suppressor gene. Mutations in both alleles are necessary to initiate polyp formation. Mutation of K-ras results in an inability to hydrolyze guanosinetriphosphate (GTP), thus leaving the G-protein permanently in the active form. It is thought that this then leads to uncontrolled cell division. MYH is a base excision repair gene, and biallelic deletion results in changes in other downstream molecules. Since its discovery, MYH mutations have been associated with an AFAP phenotype in addition to sporadic cancers. The tumor suppressor gene p53 has been well characterized in a number of malignancies. The p53 protein appears to be crucial or initiating apoptosis in cells with irreparable genetic damage. Mutations in p53 are present in 75% of colorectal cancers. (See Schwartz 10th ed., pp. 1204–1205.)

Answer 243

Answer: C A diet high in saturated or polyunsaturated fats increases risk of colorectal cancer, while a diet high in oleic acid (olive oil, coconut oil, fish oil) does not increase risk. Animal studies suggest that fats may be directly toxic to the colonic mucosa and thus may induce early malignant changes. In contrast, a diet high in vegetable fiber appears to be protective. A correlation between alcohol intake and incidence of colorectal carcinoma has also been suggested. Ingestion of calcium, selenium, vitamins A, C, and E, carotenoids, and plant phenols may decrease the risk of developing colorectal cancer. Obesity and sedentary lifestyle dramatically increase cancer-related mortality in a number of malignancies, including colorectal carcinoma. This knowledge is the basis for primary prevention strategies to eliminate colorectal cancer by altering diet and lifestyle. (See Schwartz 10th ed., p. 1204.)

Answer 244

Answer: B Adenomatous polyps are common, occurring in up to 25% of the population older than 50 years of age in the United States. By definition, these lesions are dysplastic. The risk of malignant degeneration is related to both the size and type of polyp. Tubular adenomas are associated with malignancy in only 5% of cases, whereas villous adenomas may harbor cancer in up to 40%. Tubulovillous adenomas are at intermediate risk (22%). Invasive carcinomas are rare in polyps smaller than 1 cm; the incidence increases with size. The risk of carcinoma in a polyp larger than 2 cm is 35 to 50%. Although most neoplastic polyps do not evolve to cancer, most colorectal cancers originate as a polyp. (See Schwartz 10th ed., p. 1205.)

Answer 245

Answer: C Complications of polypectomy include perforation and bleeding. A small perforation (microperforation) in a fully prepared, stable patient may be managed with bowel rest, broad-spectrum antibiotics, and close observation. Signs of sepsis, peritonitis, or deterioration in clinical condition are indications for laparotomy. Bleeding may occur immediately after polypectomy or may be delayed. The bleeding will usually stop spontaneously, but colonoscopy may be required to resnare a bleeding stalk or cauterize the lesion. Occasionally angiography and infusion of vasopressin may be necessary. Rarely, colectomy is required. (See Schwartz 10th ed., p. 1206.)

Answer 246

Answer:C Hereditary nonpolyposis colorectal cancer (HNPCC; Lynch syndrome) is extremely rare (1–3% of all colon cancers). The genetic defects associated with HNPCC arise from errors in mismatch repair, the phenotypic result being MSI. HNPCC is inherited in an autosomal dominant pattern and is characterized by the development of colorectal carcinoma at an early age (average age, 40–45 years). Approximately 70% of affected individuals will develop colorectal cancer. Cancers appear in the proximal colon more often than in sporadic colorectal cancer and have a better prognosis regardless of stage. The risk of synchronous or metachronous colorectal carcinoma is 40%. HNPCC may also be associated with extracolonic malignancies, including endometrial carcinoma, which is most common, and ovarian, pancreas, stomach, small bowel, biliary, and urinary tract carcinomas. The diagnosis of HNPCC is made based on family history. The Amsterdam criteria or clinical diagnosis of HNPCC are three affected relatives with histologically verified adenocarcinoma of the large bowel (one must be a first-degree relative of one of the others) in two successive generations of a family with one patient diagnosed before age 50 years. HNPCC results from mutations in mismatch repair genes, and like FAP, specific mutations are associated with different phenotypes. For example, mutations in PMS2 or MSH6 result in a more attenuated form of HNPCC when compared to mutations in other genes. MSH6 inactivation also appears to be associated with a higher risk for endometrial cancer. Further significance of these specific mutations remains to be determined. (See Schwartz 10th ed., p. 1207.)

Answer 247

Answer: C The objective in treatment of carcinoma of the colon is to remove the primary tumor along with its lymphovascular supply. Because the lymphatics of the colon accompany the main arterial supply, the length of bowel resected depends on which vessels are supplying the segment involved with the cancer. Any adjacent organ or tissue, such as the omentum, that has been invaded should be resected en bloc with the tumor. If all of the tumor cannot be removed, a palliative procedure should be considered, although it important to note that “debulking” is rarely effective in colorectal adenocarcinoma. If the metastatic disease is low volume (isolated or potentially resectable liver lesions) and the resection of the primary tumor is straightforward (segmental abdominal colectomy), it is probably reasonable to proceed with resection. On the other hand, if the metastatic disease is high volume (carcinomatosis), especially if the primary tumor is minimally symptomatic, the operation should be aborted in order to facilitate early systemic chemotherapy. (See Schwartz 10th ed., p. 1212.)

Answer 248

Answer: C Ulcerative colitis is a mucosal process in which the colonic mucosa and submucosa are infiltrated with inflammatory cells. The mucosa may be atrophic, and crypt abscesses are common. In long-standing ulcerative colitis, the colon may be foreshortened and the mucosa replaced by scar. Ulcerative colitis does not involve the small intestine, but the terminal ileum may demonstrate inflammatory changes (“backwash ileitis”). A key feature of ulcerative colitis is the continuous involvement of the rectum and colon; rectal sparing or skip lesions suggest a diagnosis of Crohn disease. (See Schwartz 10th ed., p. 1195.)

Answer 249

A. Segmental resection anastomosis

Answer 250

A. Colorectal cancers

Answer 251

B. Total abdominal colectomy with end ileostomy and Hartman closure of the rectum

Answer 252

D. HNPCC mutation

Answer 253

B. That she undergo formal colonic resection

Answer 254

A. In patients with lesions that have not penetrated the bowel wall, the CEA levels are usually not elevated.

Answer 255

C. Cytomegalovirus

Answer 256

A. Tubular adenoma

Answer 257

B. Posterior internal sphincterotomy

Answer 258

C. Thrombosed mixed hemorrhoids

Answer 259

A. Fistulas with an external opening anteriorly connect to the internal opening by a short radial tract.

Answer 260

C. The area of the splenic flexure

Answer 261

B. SCFA are produced by bacterial fermentation of dietary lipids.

Answer 262

A. The loss of salt and water absorption from the right colon

Answer 263

C. Bacteroides fragilis

Answer 264

B. Colorectal cancer

Answer 265

C. Colonoscopy and EGD

Answer 266

B. Wide excision For anal SCCA: Nigro protocol UNLESS - If T1N0, well-differentiated (EXCISE)

Answer 267

A. Re-stage the disease, prepare for salvage abdominoperineal excision. NCCN: Progressive Evaluate for 8-12 weeks 4-6 weeks up to 28 weeks For progressive disease, if biopsy proven, restage disease. Locally recurrent disease warrants APR + groin dissection, with positive inguinal nodes. Metastatic disease warrants 5-FU or Carboplatin/paclitaxel or FOLFOX or modified DCF. Surveillance involves inguinal node palpation every 3-6months for 5 years, Chest/abdominal/pelvic CT with contrast or chest CT without contrast and abdominal/pelvic MRI with contrast annually for 3 years.

Answer 268

B. Anal melanoma has a good response to chemotherapy and radiotherapy.

Answer 269

D. Observe until pregnancy is terminated

Answer 270

If <3 days: excisional | If >3 days: conservative

Answer 271

5-fluorouracil Mitomycin C 30 Gy of external beam radiation

Answer 272

Terminal ileum + cecum + appendix For: Ileocecal Crohn's

Answer 273

10cm of terminal ileum + ileocolic vessels + right colic vessels + right branch of middle colic For: Proximal Colon CA

Answer 274

Right colectomy + ligation of middle colic vessels at the base with a distal ileum + distal transverse anastomosis For: Hepatic Flexure or Proximal Transverse Cancer

Answer 275

Colocolonic anastomosis + Equivalent to extended right colectomy For: Mid and Distal Transverse Lesions

Answer 276

Left branches of middle colic + left colic + first branches of sigmoid with a colocolonic anastomosis For: Distal Transverse Splenic Flexure, or Descending Colon CA

Answer 277

Left colectomy + right branches of middle colic For: Distal Transverse lesions

Answer 278

Sigmoid branches + descending colon with an upper rectal anastomosis For: Sigmoid Colon lesions

Answer 279

Ileocolic vessels + right colic vein + middle colic vein + left colic vein PRESERVE the superior rectal vessels. For: Fulminant colitis Attenuated FAP Synchronous colon CA

Answer 280

Colon + rectum + anus with an end ileostomy.

Answer 281

Colon + rectum Anal sphincter muscles are PRESERVED. With an ileoanal anastomosis (with neorectum as a J, S, W ileal pouch)

Answer 282

Distal sigmoid + upper rectum with IMA + IMV ligation For: Diverticulitis

Answer 283

Rectosigmoid + IMA + IMV For: Upper + mid rectum lesions (extraperitoneal rectum 6-10cm)

Answer 284

Rectum is fully mobilized to level of levator ani muscle. Anterior dissection is extended along rectovaginal septum (females) or distal to the seminal vesicles and prostate (males) with a coloanal anastomosis

Answer 285

Colorectal resection + colostomy/ileostomy + distal rectum as blind pouch alternative: mucus fistula (if length of remaining segment will allow) For: Diverticulitis with peritonitis

Answer 286

Entire rectum + anal canal + anus + permanent colostomy from descending or sigmoid

Answer 287

* Intersphincteric resection (ISR): Remove the internal anal sphincter Partial: Surgical anal margin Subtotal: Total: Until dentate line

Answer 288

Level 0: Noninvasive (severe dysplasia, carcinoma In situ, or Intramucosal carcinoma) (0% risk of LN mets) Level 1: Invading through muscularis mucosa, but limited to the head of a pedunculated polyp (<1%) Level 2: Cancer invading the neck of a pedunculated polyp (<1%) Level 3: Cancer invading the stalk of a pedunculated polyp (<1%) Level 4: Cancer invading into the submucosa of the bowel wall below the stalk of a pedunculated polyp. All session polyps with invasive cancer are level 4 (12-25%)

Answer 289

Distance of SM In Asian SM1: Superficial 1/3 (2% nodal mets) SM2: Superficial 2/3 (8%) SM3: Deep 1/3 (23%)

Answer 290

cS1: freely mobile (submucosa) cS2: mobile with the rectal wall (muscularis propria) cS3: tethered mobility (perirectal fat) cS4: fixed (adjacent tissues)

Answer 291

4. (B) Ulcerative colitis is a disease of unknown etiology, which involves the colon and rectum and spares the remainder of the GI tract. It’s clinical course is variable with inflammatory changes and clinical symptoms ranging from mild to severe. The process is confined to the mucosa and the submucosa and does not extend through the full thickness of the bowel wall. Inflammatory changes are confluent with no skip areas. The risk of dysplasia and colorectal cancer is higher in ulcerative colitis than in the general population.

Answer 292

5. (C) Toxic megacolon is a fulminant exacerbation of ulcerative colitis, causing massive dilatation of the colon with perforation, fecal peritonitis, and death. Emergency total colectomy is indicated.

Answer 293

6. (D) Risk of dysplasia and colorectal cancer is higher in ulcerative colitis than in the general poulation. The severity, duration, and anatomic extent of the inflammation are risk factors for the development of dysplasia and cancer. These cancers do not seem to follow the adenoma carcinoma sequence and can arise in flat mucosa making them difficult to detect even with regular colonoscopies. After 8–10 years of colitis survellance colonoscopy should be performed with multiple random biopsies. The finding of dysplasia is an indiction for immediate total protocolectomy. Centers have reported up to 42% of colons removed for dysplasia also had colon cancer.

Answer 294

7. (D) The man likely has diverticulitis. The differential includes irritable bowel, appendicitis, inflammatory bowel disease, pyelonephritis, ischemic colitis, and perforated carcinoma. Diverticulitis is an infectious complication of diverticulosis resulting from perforation of the colonic diverticulum. The resulting inflammation may be confined to the pericolonic tissue (incomplicated diverticulitis) or result in abscess, free perforation, fistulization, or obstruction (complicated diverticulitis). The clinical spectrum is correspondingly broad ranging from mild symptoms to peritonitis and sepsis. Patients with signs and symptoms of sepsis should be hospitalized and undergo diagnostic study. A CT scan is the best study to evaluate the extent of the inflammatory process as well as to exclude other pathology. Plain x-ray would not reveal specific pathology. Both barium enema and colonoscopy in the acute setting are risky and may cause free perforation and contamination of the peritoneal cavity there by converting a localized process to generalized peritonitis. Barium has the additional risk of a chemical peritonitis caused by the barium itself. Diagnostic laparoscopy is invasive and may risk spreading a localized process.

Answer 295

8. (C) Diverticulitis results from acute inflammation of a colonic diverticula. The process may extend into adjacent organs (e.g., the urinary bladder and a fistula between the colon and bladder colovesical fistula may ensue). This leads to passage of colonic gas and fecal material into the bladder and urine resulting in pneumaturitis and fecaluria. Sigmoid resection and repair of the bladder fistula is indicated.

Answer 296

9. (A) Uncomplicated diverticulitis is treated with broad spectrum antibiotics and bowel rest. Surgery is not indicated—either resection or diversion of the fecal stream by colotomy or ilestomy. Anti-inflamatory agents are not indicated in the therapy of diverticulitis. The risk of a second episode is less than 30%. After a second episode, the risk is greater than 50% and resection may be advised at this stage.

Answer 297

10. (E) This patient has sigmoid volvulus. Plain abdominal x-ray shows a massively distended loop in the right upper quadrant, because the sigmoid colon, as it progressively distends, as a result of the twist of its mesentery, has no space, in the LLQ to occupy and flips over to the largest available area—namely the right upper quadrant. Given the clinical presentation and findings, the plain abdominal x-ray is diagnostic.

Answer 298

11. (E) Rigid sigmoidoscopy is effective in reduction and decompression of the volvulus, often resulting in a copious rush of gas and stool as decompression results. It also allows for evaluation of bowel viability. If the point of rotation is beyond the 25-cm rigid sigmoidoscopy, flexible endoscopy may be attempted by an experienced endoscopist using minimal inflation of air. A rectal tube should be placed to allow for bowel decompression. Laparotomy may occasionally be necessary in cases of perforation or compromised viability.

Answer 299

12. (B) Technetium sulfur colloid scans have the advantage of immediate availability but the patient must be bleeding when the isotope is injected as the isotope is quickly cleared by the reticuloendothelial system of the liver and spleen.

Answer 300

13. (B) Vasopressin can be selectively infused into a bleeding mesentric vessel. A bleeding rate of .5 per minute is necessary for a positive angiogram. Temporary success in stopping the bleeding will not obviate the need for surgery. The angiodysplasia of the colon is one of the most common causes of lower GI bleeding in elderly patients. With diverticular disease, 75% of the patients will have only a single episode of hemorrhage, whereas angiodysplasia patients are very likely to have recurrent episodes of variable severity.

Answer 301

``` 14. (C) This patient has a T2Ni stage III colon cancer for colon cancer—staging is categorized by TNM system. Where, T is depth of penetration through bowel wall, N = nodal involvement, and M = metastatic disease. T 1’s carcinoma in situ T 1 invades submucosa T 2 invades muscularis propria T 3 through the muscularis propria T 4 through visceral peritonuem N 0 no lymph node involvement N 1 1–3 positive nodes N 2 4 or more pericolic nodes N 3 any node along the main vascular M 0 no metastasis M1 distant metastasis Staging is a follows: T1 or T2 No Mo = stage I T3 or T4 No Mo = stage II Avg T N1 Mo = stage III Avg T Avg N M1 = stage IV ```

Answer 302

15. (D) Patients with stage III colon cancer have 5-year survival ranging from 20% to 50%. Prognosis is largely related to lymph node involvement. Recurrence is usually in liver, peritoneal cavity, or lungs. Adjuvant chemotherapy with 5 FU based regimens have proven benefit in decreasing recurrence and improving survival. Capecitabine is an oral fluoropyrimidine, which is converted to 5 FU in tumor cells. It’s role is still being defined in national clinical trials. Radiation therapy is not offered in stage III colon cancer as local failure is rare because adequate margins can be obtained.

Answer 303

18. (C) Crohn’s disease differs from ulcerative colitis in that clinical improvement usually occurs when a diseased segment is excluded from the fecal stream. Crohn’s disease involves the distal ileum in most patients, but almost any part of the alimentary tract could be affected. Steroids frequently result in improvement in patients with Crohn’s disease and ulcerative colitis. In Crohn’s disease, steroids are a double-edged sword, because they clearly allow initial improvement, but eventually their benefit is counteracted by adverse complications of steroids.

Answer 304

19. (C) The serosa appeared normal on inspection, but the colon mucosa was extensively involved. In ulcerative colitis, the distal rectum and colon are primarily involved in continuity to the proximal extent of the lesion. In Crohn’s disease, a similar pattern may be found on rare occasions, but other features, such as small intestinal disease, transmural involvement, skip lesions, and fistula formation, favor Crohn’s disease. The small bowel is not primarily involved in ulcerative colitis, but a “backwash” ileitis may be encountered.

Answer 305

36. (C) Both zinc and vitamin C (ascarbate) deficiency, impair wound healing. Vitamin A deficiency is also implicated in would healing and supplemental Vitamin A has been shown in experimental studies to prevent radiation included defects in wound healing. Incision through the same abdominal wall scar incision actually promotes wound healing, because the initial lag interval after creation of the wound is avoided (unless the whole scar of the incision is removed). Increase in local oxygen tension actually promotes wound healing.

Answer 306

37. (A) Doxorubicin cleaves diribonucleic acid (DNA) and has been shown to decrease wound healing. Treatment should be delayed at least 4 weeks. Wound healing will improve by reducing wound infection rates. This is the rational for the use of antibiotic prophylaxis. The use of mechanical cleansing alone will not reduce wound infection and may actually increase complications. Mechanical preparation with oral nonabsorbable antibiotics does reduce microbial flora and has been shown to reduce surgical infectious complications. Denervation of tissue surrounding the incision does not influence wound healing. Steroids delay the rate of wound healing and decrease protein synthesis.

Answer 307

45. (C) Irradiation of the abdominal cavity of more than 50 Gy is associated with a higher rate of complications. The incidence of symptomatic sigmoiditis may be as high as 75%, and histologically abnormal rectal biopsy findings occur in 11% of patients undergoing treatment for pelvic malignancy. Previous surgery with possible adhesion formation increases the risk of irradiation damage.

Answer 308

46. (E) In most patients, ischemic colitis is a selflimiting illness that usually resolves within 7–10 days. Patients may manifest pyrexia and peritonitis, have persistent symptoms, and develop complications, such as stricture formation, perforation, and bleeding. Unlike small-bowel ischemia, the main vessels are characteristically patent.

Answer 309

47. (A) The mucosa is friable and bleeds readily. Ulcers vary in size and often tend to be transverse in position and surrounded by telangiectasis. They are often more prominent on the anterior wall around the anal verge. Rectal strictures usually are located about 8–12 cm above the anal verge. Rectovaginal fistula may develop in female patients. On barium enema, a narrow stricture is difficult to differentiate from a carcinoma.

Answer 310

48. (D) In 90% of cases with colonic ischemia, the patient is over 65 years of age. Precipitating causes, such as cardiac disease, are much less frequently encountered than in small-bowel ischemia. In 20% of patients, an underlying obstructive lesion of the colon is noted. Unlike small-bowel ischemia, the pain is often insidious in onset.

Answer 311

49. (E) The classic finding of thumbprinting may be missed if the barium enema study is deferred for more than 10 days after onset of symptoms. Unlike small-bowel ischemia, the main vessels are patent in most cases.

Answer 312

50. (D) After 10 years with ulcerative colitis, the chances of developing carcinoma increase fourfold. After 20 years, the cumulative risk is 12%, and at 25 years, it is 25%. Malignancy is often detected at a late stage and has a larger percentage of synchronous lesions as compared to that seen in patients with cancer who do not have ulcerative colitis. Patients with extensive disease and those in whom the disease occurs at an earlier age must undergo careful surveillance.

Answer 313

51. (A) Occurs more frequently than in the rest of the population. The cumulative risk of developing cancer in patients with extensive ulcerative colitis is greater than in those with more localized disease (42% at 25 years). Children are more likely to have extensive disease. Colon cancer occurs more frequently in the sigmoid and rectum in ulcerative colitis, but cancer is more likely to occur in patients who have universal disease. Synchronous carcinomas in patients without ulcerative colitis occur in 4%, compared to 25% in those with colitis. Lesions usually are flat, are frequently missed at examination, and have a worse prognosis than sporadic colon cancers found in normal risk patients. Adults developing cancer under the age of 45 have a poorer prognosis than those who develop it later.

Answer 314

52. (C) There has been an increase in incidence of colon cancer relative to that of the rectum in recent years. This observation may be related to the improved diagnostic techniques now available with colonoscopy. The higher mortality of some rectal cancer patients may be attributed to an incomplete resection of the tumor when it is close to the cut edge. Each year, 14,000 new cases are diagnosed and over 6000 deaths occur.

Answer 315

53. (E) Just under half of patients with local disease will also have associated metastatic disease. Patients with microscopic lymph node metastasis—adjacent as opposed to remote— and with one to three lymph nodes involved have a better prognosis than patients with more extensive disease.

Answer 316

54. (B) Synchronous malignant lesions (present in 4–5%) refer to those present at the time of surgery or found in investigations carried out within 6 months after operation. Metachronous lesions are those not detected during this period but subsequently identified. Metachronous carcinomas occur in about 5% of cases.

Answer 317

55. (B) Synchronous carcinoma and polyps, of all types, occur at sites in the colon not included in an anterior or sigmoid resection. Both synchronous carcinomas and benign polyps occur mainly at sites in the colon that would not be included in the definite resection for the primary carcinoma. Thus, it is important to try, whenever possible, to perform colonoscopy before colon resection to facilitate planning of the operation should a synchronous lesion be detected. If this study is omitted, it is advisable to have a complete colonoscopy performed within the first 2–3 months after resection.

Answer 318

56. (C) Dukes A lesions have an excellent prognosis of 90% 5-year survival compared to that with serosal extension (B2), particularly if lymph nodes are heavily involved. Around 70 % of obstructing lesions occur on the left side and 30% proximal to the hepatic flexure. The CEAlevel correlates with the extent of encirclement of the tumor, Dukes classification, and the likelihood of recurrence.

Answer 319

``` 57. (C) The most common sites of obstruction are descending colon (21%), sigmoid (17%), and splenic flexure (15%). The percentages for cases with obstruction at a particular site are splenic flexure, 37%; sigmoid, 16%; and right colon, 14%. ```

Answer 320

58. (A) The ducts of the anal glands drain into the anus and are covered by the vertical columns of Morgagni. Infection of these glands may account for some cases of perianal abscess. The folds end distally at about the level of the dentate line. The lower third of the anus receives its nerve supply from the pudendal nerve (somatic). In order to minimize spread of infection, the local anesthetic should be confined to the skin immediately overlying the abscess. This should be performed in a hospital setting, in an operating room, with good lighting, in the lithotomy position, using a combination of IV sedation andlocal anesthesia. Protoscopy/sigmoidoscopy can be undertaken at he same time.

Answer 321

59. (C) CEA is useful in the follow-up care of patients with colon carcinoma after resection. The levels of this antigen usually come to normal after complete resection of the tumor. A subsequent elevation may suggest a recurrence of the tumor either at the resection margin or at distant sites. The sensitivity and specificity of CEA for diagnosis of colon carcinoma is poor. It has no implications for resectability of the lesion.

Answer 322

60. (E) Insidious development of a microcytic, hypochromic anemia is an important clue for the diagnosis of carcinoma of the right colon. Guaiac-positive stool with or without a palpable mass in the RLQ should raise the possibility. All the other possibilities listed may also cause lower GI bleeding but are characteristically associated with abdominal pain (peptic ulcer disease, Crohn’s disease, ulcerative colitis). Bleeding in sigmoid diverticulosis usually is bright red and painless.

Answer 323

61. (A) Recurrent fistulas in ano are a feature of Crohn’s colitis. The absence in the rectum eliminates the possibility of ulcerative colitis. Amebic colitis presents with recurrent episodes of diarrhea with bleeding. Ischemic colitis also presents with diarrhea.

Answer 324

62. (D) The picture described suggests large-bowel obstruction in a patient with a competent ileocecal valve. The most likely cause is an obstructing carcinoma. The site of obstruction is in the sigmoid colon above the level of sigmoidoscopy. Sigmoid volvulus, ischemic colitis, and diverticulitis will present some findings on sigmoidoscopy. Pseudoobstruction of the colon will manifest as colonic distention down to the rectum (Fig. 6–5).

Answer 325

63. (D) Rectosigmoid injuries should promptly raise a high index of suspicion, warranting immediate sigmoidoscopy to confirm the diagnosis. Sigmoidoscopy, rigid or flexible, involves much manipulation and insufflation of air. This is hardly desirable or safe in the presence of a significant tear in the presence of a rectal foreign body, free air under the diaphragm, in a patient with an acute abdomen, is all that is necessary to warrant laparotomy. Following this, CT scan with gastrofin administered orally, will give the diagnosis. The best treatment is exteriorisation that is colostomy, at the perforated site. This will depend upon the location and extent of the perforation. If small and localized, colostomy at the site or proximally may be chosen. If the tear is massive, then resection with proximal colostomy and mucous fistula (Hartman) may be indicated.

Answer 326

64. (C) Volvulus of the sigmoid (secondary type) is common in elderly patients who are chronically constipated. Redundancy of the sigmoid and a narrow mesenteric attachment predispose for the twisting. In the large bowel, the sigmoid is the most common site. Abdominal distention and tenderness are the common presenting symptoms. Volvulus of the sigmoid colon can usually be detected on a supine and erect abdominal x-ray. Sigmoidoscopy and contrast barium studies may be helpful to differentiate carcinoma from volvulus (Fig. 6–6).

Answer 327

65. (A) The long history of bloody diarrhea should suggest a diagnosis of inflammatory bowel disease. The acute onset of abdominal pain together with the findings of an acute abdomen and systemic manifestations should raise the suspicion of a devastating complication. The picture is characteristic of acute toxic megacolon in ulcerative colitis. All the other possibilities listed may present with an acute abdomen, but the long history should point to ulcerative colitis.

Answer 328

66. (D) In a patient with abdominal aortic aneurysm resection, the most worrisome complication is inadequate blood supply to the sigmoid colon through the marginal artery. Sigmoid ischemia should be ruled out by sigmoidoscopy. In the clinical picture described, sigmoidoscopy should be the most important test.

Answer 329

67. (B) The findings described on physical examination and CT scan are suggestive of acute diverticulitis of the sigmoid colon. The initial treatment of this condition is expectant with antibiotics with or without nasogastric drainage. An antibiotic with specificity against the Bacteroides species (third-generation cephalosporin, metronidazole, or clindamycin) should be part of the regimen. Steroids have no place in the treatment. Laparotomy is indicated only after failure of conservative treatment.

Answer 330

68. (E) The clinical picture of recurrent bright rectal bleeding that is not associated with abdominal pain is characteristic of diverticulosis of the colon. The bleeding in sigmoid carcinoma is often microscopic. Diverticulitis of the colon would present with associated pain. Adenomatous polyp may present with painless rectal bleeding, but the most common condition in this elderly age group is diverticulosis of the colon.

Answer 331

69. (E) Laparotomy and subtotal colectomy should be the preferred approach in a hypotensive patient. There is no time for trying to localize the site of bleeding by scans, mesenteric angiography, or colonoscopy. Although the common site of massive diverticular hemorrhage is the right colon, a blind right colon resection in an elderly woman with hypotension is fraught with the danger of recurrent bleeding from the left colon. The safest and most expeditious management is subtotal colectomy. The decision for anastomosis or proximal ileostomy will depend on the stability of the patient.

Answer 332

70. (A) A common cause of lower GI bleeding that is recurrent and painless is angiodysplasia of the colon. In the absence of diverticula or hemorrhoids, the suspicion is even higher for these lesions. Peptic ulcer and Meckel’s diverticulum can cause predominantly lower GI bleeding. However, the bleeding is usually in the form of melena rather than bright red.

Answer 333

71. (B) Small-bowel turnover can be measured in rats by autoradiographic studies in which turnover of cells located in the crypts migrate along the villus toward the tip over a 2- to 3- day period. Intestinal villous mucosa undergoes hypertrophy and hyperplasia whenever an increased food load continuously enters the small intestine.

Answer 334

72. (C) All the choices listed except hyperplastic polyp are precancerous lesions. The carcinomas in ulcerative colitis and familial polyposis are multicentric. Large villous adenomas may have carcinomatous changes. Any patient with a colon carcinoma is predisposed to develop a metachronous lesion in the remaining colon, hence the importance of regular follow-up examinations in these patients.

Answer 335

73. (B) All the clinical features mentioned and the strong family history should raise the possibility of familial polyposis. Although other possibilities listed may also cause rectal bleeding and abdominal pain, the strong familial history should give a clue to the diagnosis. The early onset of invasive carcinoma in these patients makes recognizing familial polyposis very important.

Answer 336

74. (E) Many patients who have metastasis to the liver or lung have resectable tumors. A reasonable disease-free interval has been reported after such resections, especially with carcinoma of the colon as the primary lesion.

Answer 337

75. (A) Cefizox is not effective against many strains of Pseudomonas. If the drug is used in pseudomonas infection a higher dosage may be indicated, and the antibiotic should be changed if a quick response does not occur. Complications include cross reactions in patients who are allergic to penicillin. It does not seem to have nephrotoxic side effects.

Answer 338

76. (A) The presence of distended loops of bowel indicate bowel obstruction. The clinical features favor mechanical obstruction rather than paralytic ileus due to infection. Obstruction due to adhesions is more common than obstruction due to hernia.

Answer 339

77. (A) This is a relatively uncommon lesion. One sign that may be elicited with a mesenteric cyst is that the swelling moves freely in the direction between the left iliac fossa and the right hypochondria (i.e., perpendicular to the smallbowel mesentery axis) (Fig. 6–7)

Answer 340

78. (B) Gallstone ileus results in “tumbling” intestinal obstruction due to the intermittent nature of the condition. Previous choledochoduodenostomy could give air in the biliary tree but not obstruction.

Answer 341

87. (C) In general, failure (or inability) to continue anticoagulants is an indication to insert an IVC filter to minimize the possibility of serious and possibly fatal pulmonary embolus.

Answer 342

91. (L) The jejunum is the first part of the alimentary tract and, therefore, is the primary site of absorption of nearly all nutrients. It is unable to absorb vitamin B12 and bile salts, which are absorbed exclusively in the ileum. If the ileum is transposed between the duodenum and the jejunum, it undergoes compensatory hypertrophy and takes over the function of the jejunum and becomes the primary site of nutrient absorption.

Answer 343

92. (M) In Hirschsprung’s disease, there is an absence of myenteric plexus in the upper anal segment (i.e., the most distal portion of the cloaca). In 15%, the myenteric plexus involves only the upper anus; in 70%, the rectum is also involved; and in 15%, part of the colon is also involved. The abnormal segment is contracted; whereas, the dilated bowel is proximal to the diseased segment.

Answer 344

93. (G) In this variety, the hernia does not have a complete covering of peritoneum. It is called a sliding hernia. It is important that the surgeon does not attempt to remove peritoneum from the circumference bowel wall where it does not exist, because the bowel will become devascularized.

Answer 345

94. (B) Perianal abscess is most common type of anorectal abscess. It is superficial and lies in perianal space. Duration of symptoms is short and patient is unlikely to have fever or leukocytosis.

Answer 346

95. (F) Ischiorectal abscesses are often large, erythematous indurated, and tender. They are often associated with fistula.

Answer 347

96. (F) Supralovator abscesses are relatively rare. Most patients have a pelvic inflammatory condition such as salpingitis, diverticulitis or Crohn’s, or have had recent pelvic surgery.

Answer 348

97. (B) A single or multiple sinuses that has an external opening in the posterior half of the skin that surrounds the anus will have an internal opening in the midline on the distal anus if a fistula has formed (Fig. 6–8).

Answer 349

98. (A) The most common site for a pilonidal abscess to develop is in the midline posteriorly in the natal cleft posterior to the sacrum.