Gastrointestinal and Abdominal: Colon

Question 1

Colon: Anatomy and Physiology

Answer 1

The colon begins at the ileocecal valve and extends

distally to the anal canal. Its primary function is the

reabsorption of water and sodium, secretion of potas-

sium and bicarbonate, and storage of fecal material.

The ascending and descending colon are fixed in a

retroperitoneal location, whereas the transverse and

sigmoid colon are intraperitoneal.

Arterial supply to the cecum, ascending colon, and

transverse colon is from the superior mesenteric artery

by way of the ileocolic, right colic, and middle colic

arteries. The remainder of the colon is supplied by

the inferior mesenteric artery by way of the left colic,

sigmoid, and superior hemorrhoidal arteries and the

middle and inferior hemorrhoidal arteries that arise

from the internal iliac artery. The inconstant anasto-

motic artery between the middle colic of the superior

mesenteric artery and left colic of the inferior mesen-

teric artery is called the anastomosis (or arc) of

Riolan

.

The interconnecting arcades in closer proxim-

ity to the mesenteric border of the colon are referred

to as the marginal artery of Drummond (Fig. 5-1).

This amalgamation of anastomotic branches runs

around the medial margin of the entire colon, from

the ileocolic artery to the sigmoid arteries. Venous

drainage from the colon includes the superior and

inferior mesenteric veins. The inferior mesenteric

vein joins the splenic vein, which joins the superior

mesenteric vein to form the portal vein. In this way,

mesenteric blood flow enters the liver, where it is

detoxified before entering the central circulation.

Lymphatic drainage follows the arteries and veins.

Question 2

Ulcerative Colitis

Answer 2

Ulcerative colitis is an inflammatory disease of the

colon with unknown cause. An autoimmune basis is

suspected. Inflammation almost always involves the

rectum and extends proximally toward the cecum to

varying degrees. The small bowel is uninvolved except

in cases of “backwash ileitis” that may occur in prox-

imal colonic disease. Extracolonic manifestations include

inflammatory eye and skin disorders, arthritis, blood

disorders, and sclerosing cholangitis.

Question 3

Ulcerative Colitis: Pathology

Answer 3

Inflammation is confined to the mucosa and submucosa.

Superficial ulcers, thickened mucosa, crypt abscesses,

and pseudopolyps may also be present.

Question 4

Ulcerative Colitis: Epidemiology

Answer 4

The incidence is six per 100,000. It is more common

in developed countries, especially among Caucasians

and the Jewish population. There is no predilection

for sex. Approximately 20% of patients have first-

degree relatives who are affected, suggesting a genetic

basis. Linkage analysis has identified an association

with HLA-DR2.

Question 5

Ulcerative Colitis: History

Answer 5

Most patients usually present in the second through

fourth decade of life. Patients commonly complain

of bloody diarrhea, mucus/pus per rectum, fever,

abdominal pain, and weight loss. A history of repeated

attacks is common. Numerous diseases are associated

with ulcerative colitis, including sclerosing

cholangi-

tis in 1% of patients, as well as arthritis, iritis,

cholan-

gitis, aphthous ulcers, pyoderma gangrenosum, ery-

thema nodosum, hemolytic anemia, and ankylosing

spondylosis. These diseases may be part of the initial

presentation.

Question 6

Ulcerative Colitis: Physical Examination

Answer 6

Abdominal pain is common. Rectal tenderness may

occur with rectal fissures. The disease may present

with abdominal distention as evidence of massive

colonic distention, a situation known as toxic mega-

colon. This may progress to frank perforation with

signs of peritonitis.

Question 7

Ulcerative Colitis: Diagnostic Evaluation

Answer 7

Plain films may show massive colonic dilation, indi-

cating toxic megacolon. Perforation will result in air

under the diaphragm. Barium enema may reveal a

“stovepipe colon” owing to loss of haustral folds, as

well as mucosal ulcerations.

Endoscopy demonstrates thickened friable mucosa.

Fissures and pseudopolyps, if present, almost always

involve the rectum and varying portions of the colon.

Biopsy shows ulceration limited to the mucosa and

submucosa. Crypt abscesses arising from the crypts of

Lieberkuhn coalesce to form ulcerations.

Question 8

Ulcerative Colitis: Complications

Answer 8

Perforation and hemorrhage may occur during a severe

attack. Obstruction may develop from stri

cture as a

esult of chronic inflammation. Toxic megacolon is

uncommon but is life-threatening if not controlled

with medical therapy. Severe inflammation causes

destruction of the myenteric plexus and muscular

layer, leading to massive distention and perforation.

Patients are invariably septic and mortality high unless

emergent subtotal colectomy is performed. Colon

cancer occurs frequently, with a risk of approximately

10% within 20 years. Once the diagnosis of ulcerative

colitis is made, routine colonoscopic surveillance is

mandatory.

Question 9

Ulcerative Colitis: Treatment

Answer 9

nitial therapy is medical, with fluid administration,

electrolyte correction, and parenteral nutrition if nec-

essary. Corticosteroids, other immunosuppressives, and

sulfasalazine are all effective. Topical mesalamine, in the

form of enemas, is effective for mild and moderate

disease. Newer immunosuppressive agents—including

infliximab, a monoclonal antibody against tumor

necrosis factor—may be useful. High-fiber diet and

bulking agents are often useful.

Indications for surgery include colonic obstruction,

massive blood loss, failure of medical therapy, toxic

megacolon, and cancer. The recommendation of pro-

phylactic colectomy for these patients is being recon-

sidered on the basis of recent data that suggest the

incidence of cancer is not as high as once thought.

When elective surgery is performed, sphincter-sparing

operations allow the ileum to be anastomosed to the

rectal stump or anus, preserving continence and bowel

movement. The ileum is fashioned into a J-pouch,

which serves the fecal reservoir role of the removed

rectum.

Question 10

Diverticulosis

Answer 10

Diverticulosis refers to the presence of diverticula,

outpouchings of the colon that occur at points where

the arterial supply penetrates the bowel wall (singular,

diverticulum

; plural,

diverticula

) (Fig. 5-2). These are

acquired or false diverticula because not all layers of

the bowel wall are included. Most diverticula occur

in the sigmoid colon (Figs. 5-3 and 5-4). Diverticulosis

is the most common cause of lower gastrointestinal

hemorrhage, usually from the right colon. Of people

with diverticulosis, 15% will have a significant episode

of bleeding.

Question 11

Diverticulsosis: Epidemiology

Answer 11

Diverticular disease is common in developed nations

and is likely related to low-fiber diets. Because of

reduced intraluminal stool volume, the normal seg-

mental colonic peristaltic contractions are extra

forceful, which increases intraluminal pressure and

causes herniation of the mucosa through the circular

muscles of the bowel wall where the marginal artery

branches penetrate. Men and women are equally

affected, and the prevalence increases dramatically

with age. Approximately one third of the population

has diverticular disease, but this number increases to

more than half of those older than 80 years of age

Question 12

Diverticulosis: History

Answer 12

Patients usually present with bleeding from the rec-

tum without other complaints. They may have had

previous episodes of bleeding or crampy abdominal

pain, commonly in the left lower quadrant.

Question 13

Diverticulosis: Diagnostic Evaluation

Answer 13

For patients who stop bleeding spontaneously, elective

colonoscopy should be performed to determine the

cause of the bleeding. If bleeding continues,

diagnostic

and therapeutic modalities include radioisotope bleed-

ing scans, which have variable success rates

, and mesen-

teric

angiography, which has an excellent success rate

in the presence of active bleeding.

Question 14

Diverticulosis: Treatment

Answer 14

Asymptomatic individuals require no treatment. In

the event of a bleed, 80% will stop spontaneously.

Elective segmental or subtotal colectomy is not usu-

ally recommended at first episode. However, depend-

ing on the ability to accurately determine the site of

bleeding, the severity of the initial bleeding episode,

and the general status of the patient, it may be indi-

cated. Patients with recurrent bleeding are usually

offered surgical resection. Active bleeding is treated

colonoscopically if the colon can be cleaned and the

bleeding site identified. Embolization of the bleeding

vessel may be possible using selective angiography. In

the face of massive bleeding, if the above methods

fail and no bleeding site is identified, emergent subto-

tal colectomy is performed. Before embarking on

such an irreversible procedure, which involves

removing most of the colon, it is of utmost impor-

tance to ensure that the bleeding source is not from

hemorrhoids or a rectal source. If a colonic bleeding

site is identified, segmental colectomy can be per-

formed, usually based on the arterial branch feeding

the bleeding site.

Question 15

Diverticulitis

Answer 15

The narrow neck of a diverticulum predisposes it to

infection, which occurs either from increased intralu-

minal pressure or inspissated food particles. Infection

leads to localized or free perforation into the abdomen.

Diverticulitis most commonly occurs in the sigmoid

and is rare in the right colon. Approximately 20% of

patients with diverticula experience an episode of

diverticulitis. Each attack makes a subsequent attack

more likely and increases the risk of complications.

Question 16

Diverticulitis: History

Answer 16

Patients usually present with left lower quadrant

pain; right-sided diverticulitis causes right-sided pain

but is less common. The pain is usually progressive

over a few days and may be associated with diarrhea

or constipation.

Question 17

Diverticulitis: Physical Examination

Answer 17

Abdominal tenderness, usually in the left lower quad-

rant, is the most common finding. Local peritoneal

signs of rebound and guarding may be present.

Significant colonic inflammation may present as a pal-

pable mass. Diffuse rebound tenderness and guarding

as evidence of generalized peritonitis suggests free

intra-abdominal perforation.

Question 18

Diverticulitis: Diagnostic Evaluation

Answer 18

Elevation of the white blood cell count is usual.

Radiographs of the abdomen are typically normal,

except for cases of perforation or obstruction. In cases

of perforation, free air is seen under the diaphragms

on chest x-ray. Computed tomography (CT) may

demonstrate pericolic fat stranding, bowel wall thick-

ening, or abscess. Colonoscopy and barium enema

should not be performed during an acute episode

because of the risk of causing or exacerbating an

existing perforation.

Question 19

Diverticulitis: Complications

Answer 19

Structure, perforation, or fistulization with the blad-

der, skin, vagina, or other portions of the bowel may

develop.

Question 20

Diverticulitis: Treatment

Answer 20

Most episodes of diverticulitis are mild and can be

treated on an outpatient basis with broad-spectrum

oral antibiotics. Combination treatment with cipro-

floxacin and metronidazole (Flagyl) is appropriate

to cover aerobic and anaerobic organisms. For severe

cases or cases in older adult patients or debilitated

patients, hospitalization with bowel rest and broad-

spectrum intravenous antibiotics (e.g., ampicillin,

ciprofloxacin, and metronidazole) are required. For

patients who do not improve in 24 to 48 hours, repeat

CT scan with percutaneous drainage of any identifi-

able abscess cavity may obviate the need for emer-

gency operation. In the event of free perforation or

failure of medical management, surgical exploration

with resection and colostomy is usually required

(Hartmann procedure; Fig. 5-5). In addition, surgical

intervention is indicated in the presence of the com-

plications previously described. With repeated attacks

of diverticulitis, the risk of developing complications

increases significantly.

Question 21

Colonic Neoplasms

Answer 21

Recent evidence suggests that colon cancer follows

an orderly progression in which adenomatous polyps

undergo malignant transformation over a variable time

period (Fig. 5-6). For this reason, these polyps are

considered premalignant lesions. Fifty percent of car-

cinomas have a

ras

gene mutation, whereas 75% have

a

p53

gene mutation.

Question 22

Colonic Neoplasms: Epidemiology

Answer 22

Colon cancer is the second most common cause of

cancer-related death in the United States. Risk factors

include high-fat and low-fiber diets, age, and family

history. Ulcerative colitis, Crohn’s disease, and

Gardner syndrome all predispose to cancer, and can-

cer develops in all patients with familial polyposis

coli if they are not treated.

Question 23

Colonic Neoplasms: Pathology

Answer 23

Adenomatous polyps are either tubular or villous,

with some lesions exhibiting features of both. The

higher the villous component, the higher the risk of

malignancy. As the lesion grows in size, the likelihood

of its having undergone malignant transformation

increases significantly. Although tubular adenomas

1 cm contain malignancy in only 1% of cases, lesions

2 cm contain malignancy 25% of the time. For

villous adenomas, the numbers are 10% and 50%,

respectively. Ninety percent of colon cancers are

adenocarcinomas, and 20% of these are mucinous,

carrying the worst prognosis. Other types include

squamous, adenosquamous, lymphoma, sarcoma, and

carcinoid. Three percent of tumors are synchronous

(occurring simultaneously), and metachronous tumors

(multiple primary cancers developing at intervals) also

occur in 3% of cases.

Question 24

Colonic Neoplasms: Screening

Answer 24

Screening is aimed at detecting polyps and early

malignant lesions. In theory, colon cancer is a prevent-

able disease, because if all patients underwent thor-

ough screening and timely polyp removal, the mor-

tality rate from colon cancer would be drastically

reduced. The current screening recommendations from

the American Gastroenterological Association divide

people into two groups: average risk and increased risk.

Average-risk persons lack any identifiable risk factors.

Increased-risk persons have either a personal history

of adenomatous polyps or colorectal cancer, first-

degree relatives with colorectal cancer or adenoma-

tous polyps, a family history of multiple cancers, or

a history of inflammatory bowel disease. Screening

should begin at age 50 years for average-risk patients

and age 40 years for increased-risk patients. American

Cancer Society guidelines for the early detection of

colorectal cancer include the following:

• yearly fecal occult blood test or fecal immuno-

chemical test

• flexible sigmoidoscopy every 5 years

• yearly fecal occult blood test or fecal immunochem-

ical test, plus flexible sigmoidoscopy every 5 years

• double-contrast barium enema every 5 years
• colonoscopy every 10 years

Patients with positive test results should be followed

up with colonoscopy.

Question 25

Colonic Neoplams: Staging

Answer 25

Generations of medical students have been confused by the various staging systems used for classifying colon cancer. Although the Dukes classification sys- tem devised in 1932 was simple and uncomplicated, it was eventually found to be inferior with respect to prognostication than the subsequently developed Astler-Coller system. Since 1991, the American Society of Colon and Rectal Surgeons have endorsed the TNM staging system, which has become the standard for modern cancer staging (Fig. 5-7). The TNM (tumor, nodes, metastases) classification system is as follows: Tis: Carcinoma in-situ T1: Tumor invades submucosa. T2: Tumor invades muscularis propria. T3: Tumor invades through the muscularis propria into the subserosa or into the pericolic or perirec- tal tissue. T4: Tumor directly invades other organs or structures and/or perforates the visceral peritoneum. N0: No regional lymph node metastasis. N1: Metastasis in one to three regional lymph nodes. N2: Metastasis in four or more regional lymph nodes. M0: No distant metastasis or residual tumor. M1: Distant metastasis present. Staging is based on a combined evaluation of charac- teristics involving the tumor, lymph nodes, and pres- ence of metastasis.

Question 26

Colonic Neoplasms: History

Answer 26

The clinical presentation of colon cancer is often dependent on the location of the lesion. Small proxi- mal ascending colonic neoplasms are often asympto- matic. Occult blood in the stool and weight loss from metastatic disease may be the only signs. As the size of a lesion increases, right colon cancers usually cause bleeding that is more significant, whereas lesions in the left colon typically present with obstructive symp- toms, including a change in stool caliber, tenesmus, or constipation. In general, this is due to fecal matter entering the right colon in liquid form and easily tran- siting a large cecal lesion, whereas desiccated stool in the left colon tends to obstruct when confronted with malignant luminal narrowing. Rectal bleeding from a low rectal cancer should never be mistakenly explained away as symptomatic hemorrhoids. Simple digital rectal examination will demonstrate the tumor and prevent delay in diagnosis. Rectal cancer also can present with passage of mucus per rectum, arising from tumor surface secretions. Complete acute large bowel obstruction may also occur. Any older adult patient who lacks a history of prior abdominal surgery or recent colonoscopy who presents with a large bowel obstruction must be considered to have obstructing colon cancer until proven otherwise. Any sizable lesion may produce abdominal pain. Perforation typically causes frank peritonitis. Constitutional symptoms, including weight loss, anorexia, and fatigue, are common with metasta- tic disease.

Question 27

Colonic Neoplasms: Physical Examination

Answer 27

Rectal examination may reveal occult or gross blood, and for low rectal cancers, the lesion can be directly palpated. For large bulky tumors, a mass may be noted on abdominal examination. Stigmata of hered- itary disorders, including familial polyposis syndrome or Gardner syndrome, may be present.

Question 28

Colonic Neoplams: Diagnostic Evaluation

Answer 28

Laboratory evaluation should include a hematocrit, which often reveals microcytic anemia from chronic occult blood loss. The liver is the most common site for metastases, and liver function tests may be abnormal. Carcinoembryonic antigen may also be obtained; although it is not a useful screening test, it is valuable as a marker for recurrent cancer. Colonoscopy has the advantage of examining the entire colon while also performing confirmatory biopsy for tissue diagnosis. Flexible sigmoidoscopy reaches up to 70 cm of the most distal large intestine, whereas colonoscopy can examine the entire colon and even intubate the distal ileum. Approximately 70% of lesions should be detected by flexible sigmoidoscopy. Rigid sigmoidoscopy is only useful for examining the lower 25 cm and is therefore often used to evaluate rectal cancers. Radiologic evaluation can be performed with double-contrast barium enema, which uses both a radio-opaque contrast medium (barium) to coat the colon wall and air to provide luminal distention. The classic finding on barium enema is a constricting filling defect, known as an apple core lesion (Fig. 5-8). CT is useful for evaluating extent of disease and the presence of metastases, particularly in the liver. Magnetic resonance imaging may be better for evaluating liver metastases but usually does not add more overall information than that which is obtained with CT. Positron-emission tomography scan is useful for showing metastatic disease or else late recurrence in a patient who previously underwent resection and who has an increasing carcinoembryonic antigen level. For rectal lesions, endorectal ultrasound is the standard of care for assessing the depth of tumor invasion and the presence of lymph node metastases.

Question 29

Colonic Neoplasms: Treatment

Answer 29

Surgical therapy of colon cancer is based on complete removal of the malignant lesion and associated lymph nodes. The oncologic principles underlying segmental colon resection for malignancy are based on the blood supply of the segment of colon containing the lesion, as well as the distribution of the parallel draining lymph node network. For cancers of the cecum and ascending colon, right hemicolectomy is indicated. Tumors of the transverse colon require transverse colectomy, with removal of the hepatic and splenic flexures. Descending colon tumors require left colec- tomy, and sigmoid tumors are treated with sig- moidectomy. Most rectal tumors are treated with low anterior resection, whereas the very low rectal can- cers near the anus occasionally require abdominoper- ineal resection, which entails resection of the anus with closure of the perianal skin and creation of a permanent end colostomy, because anastomosis may not be technically feasible. Examples of the extent of resection for different types of colectomy are shown in Figure 5-9. Historically, open surgery has been the standard approach for colon resection; however, the laparo- scopic technique has gained rapid acceptance, given the reduced morbidity compared with open surgery, in addition to studies showing the less invasive approach to be equally effective as open surgery in terms of survival. The widely quoted randomized trial results by the Clinical Outcomes of Surgical Therapy (COST) Study Group, published in 2004, showed no difference in either recurrence or 3-year survival between laparoscopic or open groups. These findings were subsequently supported by other ran- domized trials, such as the Conventional Versus Laparoscopic-Assisted Surgery in Colorectal Cancer (CLASSIC) trial from the United Kingdom, pub- lished in 2007.

Question 30

Colonic Neoplasms: Treatment: Part 2

Answer 30

In summary, despite the develop- ment of new surgical techniques, the basic oncologic goals and extent of resection should be identical, regardless of the approach. With respect to the extent of resection, guidelines from the American Joint Committee on Cancer, the American College of Pathology, and the National Comprehensive Cancer Network recommend 12 or more lymph nodes to be sampled during surgery. Thorough sampling and examination of the draining lymph nodes is thought to improve staging accuracy, which allows more appropriate adjuvant chemother- apy administration. By upstaging patients, some inves- tigators believe patients will therefore be offered more aggressive treatment that will likely result in improved overall survival.

Question 31

Colectomy: The Operation

Answer 31

Traditional preoperative preparation has included mechanical and antimicrobial bowel cleansing; how- ever, this practice is currently undergoing critical review (see Preoperative Issues in Chapter 1 for expanded discussion). Most open resections are per- formed via a midline incision. The rationale and extent of excision for various tumors is described above and in Figure 5-9. Mobilization of the right or left colon involves incising the white line of Toldt on the respective side. Care is taken to avoid the ureter, which can be injured as the colon is mobilized. Consideration of a ureteral stent should be made if the tumor is bulky and there is concern about identifying the ureter intraoperatively. The transverse colon is intraperi- toneal and does not require mobilization. Once ade- quate length of colon has been mobilized, the peri- toneum overlying the mesentery is incised to its root, and all the mesenteric vessels in the specimen are li- gated. In the open technique, noncrushing clamps are usually placed alongside the resection margin to reduce spillage, and the ends of the bowel are usually stapled and the specimen removed. Reconstruction of bowel continuity is performed with either hand-sewn or sta- pled anastomosis. For low colon or rectal anastomo- sis, use of an end-to-end anastomosis stapler placed through the anus is a preferred technique.

Question 32

Angiodysplasia

Answer 32

Angiodysplasia is being recognized with increasing frequency as a significant source of lower gastroin- testinal hemorrhage. These anomalous vascular lesions are histologically similar to telangiectasia and arise most commonly in the cecum and right colon.

Question 33

Angiodysplasia: Epidemiology

Answer 33

Angiodysplasia is one of the most common causes of lower gastrointestinal bleeding. The prevalence increases with age, to an incidence of approximately one fourth of the older adult population. Age and resulting bowel wall strain are thought to cause vas- cular tissue proliferation, leading to angiodysplastic lesions

Question 34

Angiodysplasia: History

Answer 34

Patients usually present with multiple episodes of low-grade bleeding. In 10% of cases, patients present with massive bleeding.

Question 35

Angiodysplasia: Diagnostic Evaluation

Answer 35

Diagnosis can be made with arteriography, nuclear scans, or endoscopy

Question 36

Angiodysplasia: Treatment

Answer 36

Endoscopic treatment includes electrocautery and argon plasma coagulation. Angiography with highly selective embolization or vasopressin infusion is often effective. Because many angiodysplastic lesions rebleed, definitive treatment may occasionally require segmen- tal colectomy.

Question 37

Volvulus

Answer 37

Volvulus occurs when a portion of the colon rotates on the axis of its mesentery, compromising blood flow and creating a closed-loop obstruction (Fig. 5-10). The sigmoid colon (75%) and cecum (25%) are most commonly involved. The relative redundancy of the sigmoid loop causes torsion around the mesenteric axis, whereas poor fixation of the cecum in the right iliac fossa leads to either axial torsion (cecal volvulus) or anteromedial folding (cecal bascule).

Question 38

Volvulus: Epidemiology

Answer 38

The incidence of volvulus is approximately two in 100,000. Risk factors include age, chronic constipa- tion, previous abdominal surgery, and neuropsychi- atric disorders

Question 39

Volvulus: History

Answer 39

The patient usually relates the acute onset of crampy abdominal pain and distention

Question 40

Volvulus: Physical Examination

Answer 40

The abdomen is tender and distended, and peritoneal signs of rebound and involuntary guarding may be present. Frank peritonitis and shock may follow.

Question 41

Volvulus: Diagnostic Evaluation

Answer 41

Abdominal radiographs may reveal a massively dis- tended colon with a “corkscrew” or “bird’s beak” at he point of torsion. The distended colonic loop has the appearance of a bent tire or large coffee bean.

Question 42

Volvulus: Treatment

Answer 42

Sigmoid volvulus may be reduced by enemas or endo- scopy. Rectal tubes are sometimes used to prevent acute recurrence and aid decompression. Because of the high rate of recurrence, operative repair after res- olution of the initial episode is recommended. In the acute setting and depending on the operative findings, fixation of the untwisted loop to the respective fossa may suffice for cases of viable bowel; otherwise, resec- tion is performed with either primary anastomosis or end colostomy (Hartmann procedure) in cases of sep- sis and gangrene. Treatment of cecal volvulus is usually operative at the outset, because nonoperative inter- vention is rarely successful, and the incidence of gan- grenous ischemic changes is high.

Question 43

Appendicitis

Answer 43

Appendicitis is the most common reason for urgent abdominal operation. The causes of appendiceal inflam- mation and infection are related to processes that obstruct the appendiceal lumen, thereby causing dis- tal swelling, decreased venous outflow, and ischemia. The most common extraluminal cause of obstruction is the swelling of submucosal lymphoid tissue in the wall of the appendix in response to a viral infection. This is illustrated by the incidence of viral syndromes often seen in pediatric patients shortly before devel- oping appendicitis. The most common intraluminal cause of obstruction is from a fecalith (small, firm ball of stool). Cases of obstruction with fecaliths have a higher incidence of perforation

Question 44

Appendicitis: Epidemiology

Answer 44

Children and young adults between ages 5 and 35 years are most commonly affected. Appendicitis will develop in approximately 5% of people over their lifetime. Perforation at the time of surgery is more often seen in very young children and in older adults as a result of delayed diagnosis.

Question 45

Appendicitis: History

Answer 45

Patients typically complain of epigastric pain that sub- sequently migrates to the right lower quadrant. The initial discomfort is thought to be due to obstruction and swelling of the appendix and the latter due to peri- toneal irritation. Retrocecal appendicitis may cause pain higher in the right abdomen, whereas appendici- tis located in the pelvis may cause vague pelvic dis- comfort. Anorexia is an almost universal complaint. Nausea and emesis may occur after the onset of pain. Up to 20% of patients report experiencing diarrhea, which often leads the examiner to make an incorrect diagnosis of gastroenteritis. Generalized abdominal pain may signify rupture and diffuse peritonitis.

Question 46

Appendicitis: Physical Examination

Answer 46

Low-grade fever is typical. Nearly all patients have right lower quadrant tenderness, classically located at McBurney’s point, two thirds the distance from the umbilicus to anterior superior iliac spine. Rebound and guarding develop as the disease progresses and the peritoneum becomes inflamed. Signs of peri- toneal irritation include the obturator sign (pain on external rotation of the flexed thigh) and the psoas sign (pain on right thigh extension). Rovsing’s sign is eliciting pain in the right lower quadrant on palpation of the left lower quadrant. In cases of contained per- foration, the omentum walls off the infectious process, occasionally resulting in a palpable mass in thin patients. If the perforation is free and not con- tained, then diffuse peritonitis and septic shock may develop. Rectal examination may reveal tenderness if the appendix hangs low in the pelvis.

Question 47

Appendicitis: Diagnostic Evaluation

Answer 47

The white blood cell count is usually mildly to mod- erately elevated. Urinalysis should be performed to rule out a urinary tract infection. Depending on a patient’s age, presenting history and physical examination, and available resources, radiologic studies may include ultrasound or CT scan- ning. Plain abdominal x-rays (supine and upright) usu- ally provide no useful information in confirming the diagnosis of appendicitis. Ultrasonographic evidence of appendicitis includes appendiceal wall thickening, luminal distention, and lack of compressibility. Ultrasound is also useful in female patients for demon- strating ovarian or other gynecologic pathology. CT scanning may show appendiceal enlargement, periap- pendiceal inflammatory changes, free fluid, or right lower quadrant abscess (Fig. 5-11). CT scanning is also useful for ruling in or out alter- native diagnoses, thereby reducing the negative appendectomy rate in many hospitals.

Question 48

Appendicitis: Treatment

Answer 48

Uncomplicated appendicitis requires appendectomy. Both open and laparoscopic techniques are appropri- ate. Laparoscopic appendectomy is associated with less postoperative pain, a shorter hospital course, better cosmesis, and faster return to work. Selected advanced cases with appendiceal abscess may initially be man- aged nonoperatively with antibiotics and percutaneous CT-guided abscess drainage. Once the infection has abated and the inflammatory process resolved, interval appendectomy may be performed at a later date.

Question 49

Key Points: Colon

Answer 49

Surgery for ulcerative colitis is indicated for intractable bleeding, obstruction, failure of medical therapy, toxic megacolon, and risk of cancer. • Diverticulosis is the most common cause of lower gastrointestinal bleeding. Prevalence of diverticula increases with age. Cause is related to low-fiber dietary intake. • Elective surgical therapy for diverticulitis is indi- cated for repeated attacks because of the high ecurrence and complication rate. Emergent surgi- cal therapy is indicated for free perforation and usu- ally requires segmental colon resection and end colostomy (Hartmann procedure). • Colon cancer follows a progression from adenoma to carcinoma. Adenomatous polyps are considered premalignant and must be removed entirely. Screening for colon cancer should begin at age 50 for normal-risk patients. • Surgical therapy for colon cancer is predicated on removal of the malignant lesion and the draining lymph nodes. Both open and laparoscopic tech- niques are accepted surgical therapies for resection. • Angiodysplasia is common in older adult patients and is one of the most common causes of lower gastrointestinal bleeding. • Volvulus is a life-threatening condition that pre- sents with abdominal pain and distention. • Appendicitis is the most common reason for urgent abdominal operation. Right lower quadrant abdominal pain, fever, and leukocytosis are hallmarks of the disease. Appendectomy can be performed with either open or laparoscopic techniques.