Colon & Rectum Flashcards
RUSH–COLON
With regard to the anatomy of the colon and rectum, which of the following statements is true?
A. The colon has a complete outer longitudinal and and incomplete inner circular muscle layer
B. The haustoria are separated by plicae circulares
C. The ascending colon and descending colon are usually fixed to the retroperitoneum
D. The rectum is totally invested by three complete muscle layers
E. The distal part of the recutm begins at the point where the taeniae merge
C
Colon has two muscle layers–outer longitudinal layer and inner circular layer. Inner completely encircles the colon. Outer layer is in the form of three longitudinal strips or taeniae coli that do not cover the full circumference of the colon. At the rectosigmoid junction, three taeniae coli become broad and fuse together and the return is totally invested with two complete muscle layers. (Why diverticula do not form in the rectum)
Plicae semilunares are spaced, transverse, crescentic folds that separate the tissue between the taeniae coli and form haustoria. Produce characteristic, intermittent bulging pattern that permits differentiation from of colon from small bowel radiographically. Small bowel has circular mucosal folds known as plicae circulares or valvular conniventes that traverse the full diameter for the small bowel.
Ascending and descending portions of the colon are fused to the retroperitoneum, whereas transverse and sigmoid portions are free. Anomalies of fixation seen with malrotation and volvulus are not uncommon.
Upper border of rectum is at the peritoneal reflection. Alternative definition is at the point at which the taeniae have completely merged. Rectum lacks taeniae and appendices epiploicae. The distal end of rectum is void of peritoneal covering, the middle part is covered by peritoneum centrally and upper portion is completely covered of peritoneum except for a thin strip dorsally, where the short mesorectum suspeds the rectum to the presacral tissue
RUSH–COLON
Which of the following statements is true regarding colon physiology?
A. Transit time through the colon is independent of the ferment ability of nonstarch polysaccharides such as lignin, cellulose and pectins.
B. L colon is the segment of colon where bacteria are the most metabolically active in the fermentation process. R colon is the site of storage and dehydration of stool.
C. 50% of daily energy expenditure is obtained from the absorption of short chain fatty acids by the colon; this energy is used to stimulate blood flow, regulate the pH of the colonic environment, and renew colonic mucosal cells
D. Butyrate is a short chain fatty acid and a bacterial fermentation product that is the main fuel for colonic epithelial cells
E. Colonic epithelium can use various fuels, but it prefers glutamine over n-butyrate, glucose or ketone bodies
D
Colon absorbs 1-2L of water and up to 200 mEq of sodium and chloride per day. Absorptive capacity can increase up to 5-6L/day thereby protecting the person against severe diarrhea. Cecum and R colon absorb sodium and water the most rapidly, whereas rectum is impermeable to sodium and water. Sodium is actively transports 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 ATPase and Na/K/Cl co transporters. Chloride ions are actively absorbed at the expense of bicarbonate, which is secreted in exchange. Absence of luminal chloride inhibits secretion of bicarbonate.
Main anions in stool include the short chain FA butyrate, acetate and propionate. Host and colonic bacterial flora have a symbiotic relationship: the host promotes bacteria 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. Non starch polysaccharides or dietary finer such as lignin, cellulose and fruit pectins are the main substrates for bacterial fermentation. Fermentation takes place mostly in the R colon, with the cecum being the colonic segment where bacteria are the most metabolically active.
Colonic transit time and bulking of stool are depending on the fermentability of nonstarch polysaccharide. The transit time of stool through the colon is also dependent on stool pH, ANS, and gastrocolic reflex (postprandial increase in electrical activity and colonic tone)
RUSH–COLON
Pregnant 32F admitted for severe abdo pain and diarrhea. Recently d/c’ed from hospital after having been tx for pyelonephritis. Plain films show distended colon. She underwent flex sig which reveals pseudomembranous colitis. Which statement is true regarding her condition?
A. Diarrhea that begins 1 wk after Abx use has been d/c’ed rules out PMC
B. PMC does not occur in the absence of abx therapy
C. Administration of PO vanco is appropriate tx
D. Relapse rate of 50% after tx
E. Use of alcohol based hand gels by health care workers helps eliminate spread of this disease in a hospital
C
Pseudomembranous colitis seen with incr freq and is assoc with the use of many abx. Disease has not been described with the use of vanco with with antimicrobials used to tx mycobacteria, fungi or parasites. Evidence that abx change the intracolonic flora and allow overgrowth of clostrium difficile, which then produced enterocolitis. Also evidence PMC is infectious and spread by patient to patient or staff to patient contact
Should be suspected in any patient in whom diarrhea develops during or up to 3 wks after cessation of Abx. Dx is established endoscopically by visualizing characteristic raised mucosal plaques or by cytotoxic assay for C. Diff exotoxins, which usually has a + result in patients with PMC.
Therapy should begin with prompt cessation of offending Abx. PO vanco (125 mg PO QID x 10 days) or PO/IV Flagyl (250-500mg IV QID x 7-14 days) has been used to tx this condition. PO vanco is safe for use in pregnant women.
Relapse rate is 20% with vanco and 23% with metronidazole. Most cases of C diff colitis can be successfully tx medically. Indications for surgery include: >65 y.o, immunocompetent, severe leukocytosis, and lactic acidosis. Tx is subtotal colectomy. 30 day mortality is 53%. Independent predictors of 30 day mortality are leukocytosis >50, lactate > 5, older than 75 y.o. , immunosuppression and shock requiring vasopressors
RUSH–COLON
With regards to amebiasis, which of the following statement is true?
A. Most ppl in the US are asymptomatic carriers
B. Entamoeba histolytica antibodies are detectable in serums > 90% of those with active amebiasis
C. Acute amebic dysentery closely resembles fulminant UC and should be treated aggressively with steroids
D. Amebic abscess of the spleen is the most common complication of amebic colitis
E. Perforation of the colon with peritonitis occurs in ~1/2 of patients with an acute manifestation
B
Amebic colitis is caused by protozoan Entamoeba histolytica, which infests primarily the colon and rectum and secondarily, liver. 10% asymp carriers. Transmission through food or water contaminated with feces containing entamoeba cysts. Acute and chronic forms.
Findings similar to acute UC (i.e. Fever, cramps, and blood diarrhea). Distinguishing between the two is important. Steroids are given routinely on a short term basis to treat UC but are contraindicated in tx of amebic dysentery.
Proctosigmoidoscopy would reveal extensive ulceration of intestinal epithelium and warm saline prep of the stool usually demonstrates numerous trophozoites containing ingested erythrocytes. Dx strengthened by a serologic test for E histolytica antibodies, which has a + result in 90% of patients with active amebiasis. Perforation of colon during acute form of disease is rare. Amebic abscess of liver is most common complication of amebic colitis, which may in turn rupture into the pleura, pericardium or peritoneum. Tx is Flagyl 750 mg TID for 10 days
Chronic amebic dysentery is more common and is characterized by 3-4 foul smelling BMs/day, along with abdo cramping and fever. Dx is more difficult to establish b/c cysts or trophozoites are not always demonstrable in stool prep and findings on sigmoidoscopy are N in up to 30%. E histolytica antibodies should be detectable. Tx is diiodohydroxyquin 650 mg TID x 20 days and flagyl or diloxanide furoate 500 mg TID x 10 days
RUSH–COLON
Which disease is correctly matched to the appropriate treatment?
A. Actinomycosis: Penicillin and drainage
B. Lymphogranuloma venereum: penicilllin and steroids
C. TB enteritis: isoniazaid and colectomy
D. Yersinia infections: flagyl and appendectomy
E. Entameoba histolytica: flagyl and R hemi
A
Actinomycosis = supparative, granulomatous disease caused by actinomyes israelii, an anaerobic, gram + bacterium that produces chronic inflammatory induration and sinus formation. Part of normal flora. Infections in cervicofacial area, thorax or abdo. Cecal region most frequent site of abdo infection, with a pericecal mass, abscesses, and sinus tracts. Rectal strictures reported as well. Tx consists of surgical drainage and penicillin or tetracycline
LGV is a STD caused by chlamydia trachomatis. Most frequently in men who have sex with men. Starts as proctitis and produces tenesmus, discharge and bleeding. Perianal and rectovaginal fistula may develop as well as rectal strictures. Dx with frei intracutaneous test or by complement fixation test. Tetracycline is curative and steroids have been recommended
Tuberculous enteritis seen most commonly in ileocecal region and occasionally leads to stenosis of distal ileum, cecum, and asc colon. Endoscopic and radiographic features similar to Crohn’s. Sx reserved for patients with obstruction, megacolon or perforation. Tx with amiosalicylic acid and streptomycin.
Yersinia cause by gram neg rods that is transmitted through food that is contaminated by urine or feces . Produces clinical picture indistinguishable from appendicitis. May also cause gastroenteritis, which primarily the ileocecal region. Responds to tx with tetracycline, streptomycin, ampicillin or kanamycin
Amebic colitis is caused by protozoan Entameoba histolytica which infects primarily the colon and rectum and secondarily, organs such as the liver. 10% asymptomatic carriers. Transmission of dishes is through food or water contaminated with feces Entameoba cysts. Acute or chronic. Tx is flagyl 750 mg PO TID x 10 days.
RUSH–COLON
With regard to ischemic colitis, which of the following statements is true?
A. The most common symptoms are lower abdo pain and BRBPR
B. Occlusion of the major mesenteric vessels is responsible for producing ischemia in most cases
C. Splenic flexure and hepatic flexure are the most vulnerable areas, although any segment of the colon may be involved
D. Non op management is not justified b/c in a significant percentage of such patients, perforation and peritonitis eventually develop
E. Griffith point is the vulnerable area at the rectosigmoid junction
A
Ischemic colitis should be considered in the ddx of any elderly pt with LLQ pain. Found in individuals of any age in assoc with hypercoagulable state, periarteritis nodosa, SLE, RA PCV and scleroderma. Clinical syndrome depends on 1) extent and duration of vascular occlusion, 2) adequacy of collateral circulation, 3) extent of septic complications. Appears to be a disease of small arterioles. Can occur in any segment of large bowel but most commonly seen in the splenic flexure or distal sigmoid colon due to suboptimal blood flow in areas positioned between two vascular systems (watershed area) that rely on an intact but meandering artery for blood supply.
Sudeck point is area between blood supply from last sigmoid artery and the superior rectal artery. Clinical significance is questionable b/c of retrograde flow from the middle and inferior rectal arteries. Griffith point is vulnerable area at the splenic flexure that is positioned between areas perfumed by the L branch of the middle colic artery and the asc branch of the L colic artery.
Dx is made by endoscopic exam showing cyanosis, edematous mucosa that may be covered with exudative membranes or barium enema showing typical thumb printing of bowel wall.
If ominous physical findings such as involuntary guarding or rebound tenderness, studies are contraindicated and prompt exp lap.
Transient ischemic colitis usually response to nonop management. Ischemic strictures may be resected electively with primary anastomoses after the initial ischemic episode has subsided. If sx is needed for peritonitis and gangrenous colitis, resection with end colostomy is preferred option.
RUSH–COLON
72F with PMHx: HTN, afib,and recent hemorrhagic stroke is noted to have an episode of dark blood stool. Abdo is diffusely tender on palpation. As a result of her stroke, her anticoagulation was d/c’ed 3 wks earlier. Patient undergoes exp lap, which reveal as the presence of ischemia of the small bowel, cecum and ascending colon and a normal distal colon and rectum. Which statement is most correct concerning intestinal blood flow?
A. Ischemia of the colon is caused by lack of blood flow to the ileocolic, right colic and middle colic, which originate from the SMA
B. Rectum receivers its blood supply from the superior and middle rectal arteries, which originate from the IMA
C. ~20% of intestinal blood flow circulates to the mucosa and submucosa, and the remaining 80% passes to the serosa and muscularis layers
D. Colon and small bowel are equally vulnerable to ischemic injury produced by acute reductions in blood flow
E. An increase in functional motor activity of the colon is accompanied by a corresponding increase in blood flow
A
Mesenteric vascular anatomy has a vast amt of collateral blood flow. Especially noted when a patient has experience chronic occlusion of one or more branches over time. Sudden occlusion of a main branch may be poorly tolerated.
R and transverse colon are derived from midgut and receive their blood supply from SMA, via ileocolic, R and middle colic branches. L colon and sigmoid derived from hindgut and supplied by L colic and sigmoid branches from IMA. Rectum, a hindgut structure, is supplied by the superior hemorrhoidal artery (from IMA) and middle and inferior hemorrhoidal arteries (from internal iliac or its internal pudendal branch). Venous and lymphatic drainage systems of the colon and rectum generally parallel the arterial supply with exception of the IMV which courses cephalad to empty into the splenic vein
Total blood flow to GI tract is ~25 cc/kg/min or 20% CO. During a meal, blood flow to the intestines rises to 50% above normal without a corresponding rise in CO. Physical exercise, in contrast, doubles CO with a 20% decrease in SMA flow.
~80% of blood flow to the wall of the colon reaches the mucosa and submucosa, remaining 20% supplies the muscularis. Despite extensive collateral vessels to the colon, it receives only 50% of the blood flow that the small intestine does. Colon is more sensitive to ischemic injury during acute reductions in blood flow. In contrast to other areas of the body, an increases in functional motor activity of the colon does not result in a parallel increase in absolute colonic blood flow.
RUSH–COLON
56M is schedules to undergo a lap segmental colectomy for dx of carcinoma of the desc colon. Which of the following statements is true concerning bowel prep for colorectal operations?
A. Preop nonabsorbable PO abx are effective in preventing post op wound infections
B. Preop mechanical bowel cleansing alone is most effective in preventing post op wound infections
C. Administration of broad spectrum Abx should be administered in immediate perioperative period
D. Mechanical cleansing with sodium phosphate is preferred in patients with renal insufficiency, cirrhosis, ascites and CHF.
E. Complete bowel obstruction and perforation are relative contraindications to mechanical cleansing but can still be used in select patients
C
Colon contains higher concentration of bacteria, both aerobic and anaerobic, than any other are of the body and infectious complications constitute the majority of morbidity of colorectal operations. Bacteroides is the most common anaerobe and E. coli is the most common aerobic organism found in colon.
Mechanical cleansing of the colon can be achieved by a cathartic in combination with enemas or by per oral lavage with a nonabsorbable PEG solution administered the afternoon before surgery. The need for bowel prep before colectomy has been questioned. Suggested that usage does not decrease incidence of post op septic complications, and it may be assoc w/incr morbidity. Oral and rectal sodium phosphate has the benefit of mechanically cleansing the bowel with less value. It’s use has been assoc with significant complications so it is no longer indicated for bowel prep. Complete bowel obstruction and perf are absolute contraindications to mechanical bowel prep.
Combo of mechanical bowel prep and nonabsorbable oral abx effective against both aerobic and anaerobic colonic flora have never proved to decrease postop septic complications. Systemic abx after often combined with lavage and PO abx but such as combo has not been conclusively demonstrated to confer an advantage over the use of lavage and PO abx alone.
Administration of systemic abx in place of oral abx is effective method of abx ppx and may surgeons have resorted to this to avoid nausea assoc with PO Abx. Broad spectrum parenteral abx should be administered within 30 min of skin incision to provide adequate coverage against both aerobes and anaerobes.
RUSH–COLON
Common causes of colorectal anastomotic breakdown include all of the following except:
A. Poor blood supply to the bowel edges B. Short rectal stump C. Inadequate bowel mobilization D. Hand sewn anastomoses E. Poor technique
D
Causes of anastomotic leak can be divided into implicated and definitive factors.
Implicated factors include the use of drains, advanced malignancy, shock, malnutrition, emergency surgery, smoking, steroids, male gender (narrow pelvis), and technical reasons (i.e. Tears from stapling devices).
Definitive factors include poor blood supply to the anastomoses and tension on the staple line. Anastomoses that are below the peritoneal reflection and the length of rectal stump are risk factors for leaks because of the increasing difficulty in performing the anastomoses. In addition, the environment of the anastomoses (such as radiation therapy, emergency operations and contaminated fields) may also contribute to leaks. Patients with crohn’s have a higher incidence of leaks. No difference between hand sewn and stapled anastomoses.
RUSH–COLON
Which of the following is the best initial management for acute colonic pseudo-obstruction (Ogilvie’s syndrome)?
A. Colonoscopy B. Rectal tube decompression C. NG tube decompression and correction of electrolytes D. Neostigmine E. Lower GI and gastrograddin enemas
C
Ogilvie’s syndrome involves distension of the colon without evidence of mechanical obstruction and has been assoc with use of opiates and neuroleptic meds, diabetes, myxedema, scleroderma, uremia, hyperparathyroidism, lupus, Parkinson’s, RP hematoma, and severe metabolic illness. Pathophysiology is unclear.
Thought to involve an imbalance in neural input to the colon, distal to the splenic flexure and result in contraction of the distal part of the colon and functional obstruction. Frequently, right and transverse sections of the colon are dilated with a decompressed distal colon that contains some air on plain radiographs. Risk of ischemia incr with cecal diameter >12cm. Obstipation present in up to 40%.
If hemodynamically stable, no peritonitis, and without known mechanical obstruction, management includes hydration, mobilization, correction of lytes, avoidance of offending drugs such as opiates, placement of NG, tap water enemas, and serial abdo exams.
Mechanical obstruction should be r/o with contrast enhanced enema. Although colonoscopy is the initial management for sigmoid volvulus in that it can be both diagnostic and therapeutic, it is an alternative diagnostic tool to evaluate for mechanical obstruction when Ogilvie’s syndrome is suspected and it could be used therapeutically to decompress the colon if aforementioned measures fail. 70% improve with conservative mgmt in 48 hrs.
Neostigmine and colonoscopy should be considered if conservative tx fails to resolve the symp beyond 48 hrs. It is a cholinesterase inhibitor that can cause bradycardia. All patients receiving neostigmine must be placed on a cardiac monitor and atropine must be available if bradycardia occurs. Placement of rectal tube is rarely effective b/c the tube cannot be advanced blindly into the proximally distended colon. Patients who fail conservative therapy should be considered for surgery. Options include cecostomy placement or resection if the cecum is ischemic or perforated
RUSH–COLON
In the US, what is the most common cause of mechanical obstruction of the colon?
A. Adhesions B. Diverticulitis C. Cancer D. Volvulus E. Inguinal hernia
C
When patient has sign and symptoms of obstruction, define the level of obstruction. Colonic obstruction suggested by gas pattern on plain X-RAY and can be confirmed radiographically by enema with water soluble contrast. Barium not used due to concern of causing peritonitis in the presence of a perforating lesion. Another is inspiration proximal to a partially obstructing cancer or diverticulitis, which converts a partial obstruction to a complete obstruction
CRC. Is the leading cause of bowel obstruction in US. Diverticulitis is next most common cause. In some places (i.e. Iran, Iraq, and Pakistan) where there is a high fibre content in the diet resulting in large volumes of stool and an elongated colon, volvulus is the leading cause of obstruction. In US, sigmoid volvulus is rare and usually seen in elderly, institutionalized pts. Intussusception is a common cause of colonic obstruction in infants and children but unusual in adults unless a neoplasm has precipitated it. Unlike small bowel, it is highly unusual to have obstruction of large bowel from adhesions or incarceration from a within an inguinal hernia. Other causes of LBO include fecal impaction, benign strictures secondary to ischemia or IBD
Neglected obstruction can be fatal. Colon obstruction in the presence of a competent ileocecal valve creates a closed loop phenomenon. Progressive distension of colon between point of obstruction and ileocecal valve may lead to necrosis and perforation. Volvulus can behave in the same manner and have the same consequences.
RUSH–COLON
74M adm to hosp for abdo pain and obstipation. Plan radiographs are taken showing a loop of bowel formin and inverted U shape and pointing to LUQ. Which statement is true about this patient’s dx?
A. Patient has cecal bascule, which is usually caused by twisting segment of bowel on a narrow mesentery
B. Patient has a cecal volvulus, which is tx by non op reduction in 70% of patients
C. Patient has a cecal volvulus, which is commonly associated with signs of SBO and is seen in elderly debilitated persons w/psych or neuro diseases
D. Patient has a sigmoid volvulus, which is commonly assoc w/signs of SBO and is seen in elderly debilitated persons with psych or neuro diseases
E. Patient has a sigmoid volvulus, which is initially tx by non op reduction in up to 70% of patients
E
Patient has sigmoid volvulus. Pre-requisite for development of sigmoid or cecal volvulus is mobile segment of bowel that can rotate around a mesentery whose points of fixation are in close proximity.
Cecal volvulus is found most freq in ppl 25-35 yrs. Sigmoid volvulus is more common in elderly, debilitated ppl or in those with psychiatric or neuro disorders in which immobility, meds that impair bowel motility, and loss of accessory defecatory muscles may lead to constipation and elongation of colon.
Both types of volvulus cause abdo distension and pain. With cecal volvulus, there may be radiographic evidence of SBO. With sigmoid volvulus, distended twisted loop has fairly characteristic of a bent inner tube
For sigmoid volvulus, endoscopic detorsion plus insertion of rectal tube to evacuate voluminous fecal contents is the preferred initial therapeutic approach but should be attempted only if the mucosa does not appear gangrenous. Should not be attempted if patient has rebound tenderness or other signs of peritoneal inflammation. Non op detorsion successful 70% of the time, recurrence rate of 33% to 60 % mandates elective resection of elongated colon if patient believed to have acceptable operative risk
Nonop colonoscopic reduction of cecal volvulus is successful in only 25% and should not be attempted in those with peritoneal inflam. If a colonoscopy is unsuccessful or contraindicated (i.e. When tender), an operation is indicated as soon as the patient can be prepared. In the absence of vascular compromise, cecopexy with or without cecostomy is sufficient. The most important determinant of pt 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
RUSH–COLON
20 healthy, active man with no prev medical problems is being evaluated for chronic constipation. His lytes are normal. He denies recent travel and is not currently taking any meds. Plain X-RAY show a dilated colon. Transit studies are abnormal with slow transit times. What is the next best step in mgmt of this patient?
A. Flex sig
B. Modification of diet and Abx
C. Placement of rectal tube proximal to the normal caliber aganglionic bowel to decompress the dilated non diseased bowel
D. Anal manometry you, rectal biopsy and barium enema
E. Exp Lap
D
Should be evaluated for Hirschsprung disease. Megacolon may be congenital or acquired. Both forms characterized by dilation, elongation, and hypertrophy of colon proximal to a segment of non peristaltic collapsed bowel causing obstruction. Infection with trypanosoma cruzi, Hirschsprung’s disease and neuronal intestinal dysphasia should all be considered in patient with slow transit constipation and megacolon.
Hirschprung’s is caused by congenital abscence of ganglion cells in the myenteric plexus of the bowel, which results in loss of peristaltic activity in that segment of intestine. Rectosigmoid region is most frequently involved, with variable extension of disease proximally. Transition zone from N bowel, which is dilated to the abnormal bowel, which is aganglionic, aperistaltic and of normal or decrease calibre.
Although primarily a disease of infants and children, occasionally it does not appear until later in life if an ultra short distal rectal segment is involved. In these cases, patients relate a hx of constipation dating back to infancy. Dx is apparent during first 24 hrs of life if the infant fails to pass meconium. Rectal bx is diagnostic. In adolescent and young adults, it can be dx by anal manometric measurements. If the disease is present, normal relaxation of the internal sphincter , which is the expected response to rectal distension is lost. Tx is primarily surgical and involves the use of a coloanal anastomosis.
Acquired megacolon may be seen in patients with protozoal colon infections with T cruzi, which is endemic in South and Central America. Condition has not been reported in N America. Causes widespread destruction of intramural nervous system. Acquired megacolon also occurs in patients with colonic dilation as a result of chronic constipation b/c of the loss of voluntary defecatory muscles (i.e. Paraplegia), extreme inactivity (i.e. Poliomyelitis), or voluntary inhibition of defecation (i.e. In psychotic disorders). Resection of excessive redundant colon is occasionally justified in the latter group. Patient does not related a hx of T cruzi infection or neuro disorder.
RUSH–COLON
Which of the following is true regarding rectal prolapse?
A. The extruded mucosa has radially orientated folds
B. Rectal prolapse occurs mostly in men with a male to female ration of 6:1
C. Altemeier procedure involves full thickness resection of the prolapse rectum through a perineal incision
D. Fecal incontinence is not a predominant symptomatic feature in rectal prolapse
E. Rectal prolapse is commonly attributed to intussusception of the rectum as a result of a neoplasm forming a lead point
C
Pelvic floor disorder that is commonly found in women with 6:1 F:M ration. Bimodal distribution of incidence, with peak onsets within the 1st three years and after the 7th decade of life.
Varying degrees of prolapse–internal intussusception or occult rectal prolapse (of rectal wall without protrusion through anus), providential (complete protrusion of all layers of the rectum) and mucosal prolapse.
Rectal prolapse is differentiated from incarcerated internal haemorrhoids by close exam of the mucosal folds. Hemorrhoids have radially invaginated tissue, which distinguishes hemorrhoidal cushion beds. Rectal prolapse has concentric folds.
Pathophysiology is not clear. Weakness in pelvic floor results in full thickness intussusception of the rectum through anal canal. Anorectal physiology studies have indicated that proximal pudendal nerve injury contributes to pelvic floor weakness. Direct trauma, obs injury, neuropathic diseases such as diabetes, and neoplasms involving the sacral nerve root can all lead to pudendal nerve damage. Even though neoplasm is a common cause of adult small bowel intussusception, it is not usually the cause of rectal prolapse.
Most common symptom is sensation of anal mass that reduces with manual pressure. Protrusion usually occurs with increased abdo pressure such as during coughing or defecation. Fecal incontinence is a predominant sympt in 50-75% of patients. Other symptoms include tenesmus and rectal pressure.
Operative repair can be done through abdominal or perineal approaches. Abdominal involves resection of redundant sigmoid colon and rectopexy. Approach is generally reserved for healthier patients who can tolerate abdominal surgery. Either an open or lap approach can be used. Recurrence is low. Altemeier is perineal approach that involves proctosigmoidectomy with full thickness resection of redundant rectum while prolapsed. An anterior levatorplasty is also often performed with this procedure to correct the weakness of the pelvic floor muscles assoc with this condition
RUSH–COLON
Which of the following is a common cause of massive colonic bleeding?
A. Cancer B. UC C. Diverticulosis D. Diverticulitis E. Granulomatous colitis
C
Diverticulosis and angiodysplasias are responsible for most cases of massive colonic bleeding. Although their relative freq may vary, they are the two most common reasons for LGIB. These two entities frequently coexist and precise identification of the bleeding may require endoscopic, radiographic and histologic methods.
Cause of angiodysplasia is not known. May be related to degenerative changes assoc with aging and intramural muscular hypertrophy that obstructs submucosal veins and leads to dilation and propensity of these veins to bleed. Almost all cases of colonic angiodysplasia are located in the cecum and R colon. Bleeding is venous and not as severe.
Diverticulosis can also cause massive bleeding and is attributed to ruptured vasa recta at the apex or neck of diverticulum. Diverticulitis can likewise cause bleeding as a result of mild superficial mucosal ulceration but such bleeding is usually mild.
UC is more likely to cause mild to moderate bleeding and is frequently assoc with diarrhea and systemic signs of a chronic illness, such as wt loss and failure to thrive.
Colon cancer generally causes occult rather than massive GI bleeding
RUSH–COLON
21F noted to have persistent bloody diarrhea, abdo cramps, and fever. Stool studies are neg for infectious diarrhea. Colonoscopy reveals friable mucosa in a continuous manner from the rectum to the sigmoid colon. No granulomas are found on bx. What statement is true regarding the most likely dx in this patient?
B
Patient probably has UC. In UC, anus is spared whereas in Crohn’s, anal or perianal disease is the 1st manifestation in 25-30% of patients. 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 UC (95% vs 50%).
Small bowel is extensively involved in 50% of patients with Crohn’s disease, whereas “backwash ileitis”, a nonspecific dilation of the TI, occurs in only 10% of patients with UC and has no prognostic or physiologic implications.
Clinical features of these two entities are similar: chronic diarrhea, cramping, abdo pain and fever. Blood stools, common with UC, are less frequent with Crohn’s disease. Total protocolectomy or colectomy, rectal mucosectomy, and ileal pouch-anal anastomosis eliminate UC, whereas there is no curative operation for Crohn’s.Even after total proctocolectomy for pancolonic involvement of Crohn’s, its recurrence rate may be as high as 50%. 1/3 of patients require additional surgery for such recurrence. Toxic megacolon can be an emergency, life threatening complication of either UC or Crohn’s, although it occurs less frequently with the latter.
RUSH–COLON
With regard to diverticular fistula, which of the following statements is true?
A. Colocutaneous fistulas occur spontaneously
B. Patients with colovesicular fistulas normally have urinary tract infections that may be accompanied by pneumaturia and fecaluria , and the dx is best confirmed with a barium enema
C. Coloenteric fistulas may be totally asymptomatic
D. Surgical correction is best accomplished in stages
E. Colonic fistula occurs in up to 30% of complicated cases of diverticulitis
C
Fistula formation occurs in 5% of complicated cases of colonic diverticulitis. Fistulas are usually adjacent to viscera–bladder, uterus, vagina. Colocutaneous fistulas rarely form spontaneously. They are most commonly seen as postop complications in which they drain through operative incisions or drain tracts.
Colovesical fistulas are most frequently the result of diverticular disease, followed in freq by cancer, Crohn’s, radiation induced colitis, and foreign bodies. Their 1st sumps (e.g. Fecaluria and pneumaturia) are referable to the urinary tract. Patient may have hx of abdo pain and fever before development of fistula.
Although barium enema may give info regarding the site and extent of involvement of the colon with diverticulosis, a fistula is demonstrated in only one half of the cases. Cystoscope may demonstrate bullous (edematous) edema of the done of the bladder, a finding consistent with a fistula. CT may reveal a constellation of findings including air in the bladder, a thickened loop of bowel lying adherent to the bladder and enteric contrast in the bladder (before IV contrast has been administered). CT has become the diagnostic test of choice.
Coloenteric fistulas may cause no symptoms or may be manifested as diarrhea, depending on which segments of bowel are involved with the fistula.
Fistula can be corrected in a one stage operation in most patients, which is preferred treatment. If bowel prep is inadequate or there is extensive local inflamm or abscess formation beyond immediate vicinity of colon or its mesentery, staged procedures may be required.
RUSH–COLON
Cecal diverticula are different from sigmoid diverticula in that:
A. Sigmoid diverticular are true diverticula
B. Cecal diverticulitis is usually indistinguishable from cancer
C. Cecal diverticular are considered congenital in origin
D. Asymptomatic cecal diverticular found on barium enema should be tx operatively b/c of high incidence of complications
E. In presence of feculent peritonitis from perforation of a cecal diverticula, resection and primary anastomosis can be performed safely in most cases
C
Sigmoid diverticular lack a muscular component and thus are not considered true diverticula. R sided diverticular may occur as part of diffuse colonic diverticulosis and are therefore pseudo diverticular and acquired. Occasionally, isolated, solitary, R sided diverticular are found and possess all layer of the bowel wall. They are probably congenital in origin. Cecal diverticulitis is uncommon and the correct pre-op diagnosis is rarely made b/c it is confused with acute appendicitis in 80% of patients and with cancer in approx 5%. In patients with repeated attacks, the cecal inflam and subsequent scarring and fibrosis may be indistinguishable from those assoc w/cancer. Similarly, an inflammatory mass of the sigmoid colon may resemble a cancer at laparotomy.
Surgical options depend on extent of inflam. If inflamm is minimal and limited, segmental resection and anastomosis may be all that are necessary. If there has been a perforation with frank feculent peritonitis most surgeons hesitate to perform a primary anast and instead resect the involved segment and divert the stool proximally. For both types of diverticulitis, surgical therapy is not required if the diverticulum is discovered incidentally and the patient is asymp.
RUSH–COLON
Which of the following disease processes warrants colonoscopy?
A. Determining the extent of UC in a patient in a toxic condition admitted to the hosp for an acute exacerbation
B. Management of patients with recurrent anal fistula and fissures
C. Evaluation of an equivocal findings on CT in a febrile patient with an acute exacerbation of diverticulitis
D. Evaluating GI symptoms such as rectal bleeding and severe abdo pain in a patient in an ICU with recently underwent repair of an AAA
E. Evaluation of the radiologic findings of a sigmoid colon cutoff sign and free air under the diaphragm in a patient with an acute abdomen
B
RUSH–COLON
Colonoscopy is indicated in the following group of patients except:
A. Patients with Crohn’s to monitor the efficacy of tx
B. Patient with 8 to 10 year hx of UC involving the entire colon
C. Family members at risk for HNPCC
D. A patient with an adenomatous polyp in the upper part of the rectum on sigmoidoscopy
E. Patients with CRC in a 1st degree relative
A
Different colonic diseases have different indications for and contraindications to colonoscopy
A
IBD
-Endoscopy is essential for dx and tx of IBD. Not indicated simply for purpose of monitoring response to therapy; this can be performed on clinical basis alone. Pts w/hx of UC for >8-10 yrs are at higher risk for adenoca of the colon and bx of multiple site for determination of dysplasia. Should be done annually or every other year, even if disease is in remission. Patients with IBD appear to be at higher risk for cancer than those with limited left sided disease but the latter group should also undergo surveillance. For Crohn’s disease, risk for cancer and indication for colonoscopy are less well understood. Patients with recurrent or multiple anal fistulas and fissures should undergo colonoscopy to exclude Crohn’s. If the ileum is not intubated, a small bowel radiograph should be obtained. Colonoscopy should not be performed during acute manifestations of IBD b/c of 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 done after the acute inflammation has resolved to evaluate for cancer
Polyposis syndromes
-Some authors advocate flex sig for screening at risk patients with a famhx of familial polyposis. B/c colonic polyps rarely develop in the absence of rectal polyps, it is probably not necessary to examine more proximal than the area normally covered by a flexible 60 cm sigmoidoscope.
Hereditary non polyposis colon cancer
-Beginning at age 20 or 10 yrs younger than the earliest cancer case in the family, colonoscopy should be performed q2 years
Routine Screening
- Gold standard for screening for colon cancer
- In general population, screening can begin at age 50.
- For those at risk (i.e. Strong family hx), screening should begin 40 yrs of age.
- Scope q 5-10 yrs is adequate for screening the asymp population
- CT colonography is indicated for patients whom colonoscopy was incomplete b.c of a tortuous sigmoid colon or pain.
- Colonoscopy may confirm or refute suspected or equivocal radiographic findings during a barium enema exam. 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%)
Volvulus/Pseudoobstruction
-Colonoscopy is indicated for patients with sigmoid volvulus and pseudo-obstruction of the colon, provided there are no signs of peritoneal inflammation. Decompression of the distended colon can be achieved successfully with minimal patient prep.
RUSH–COLON
A 68M adm to hospital after having passed three large maroon colored stools. On arrival at hospital, he passes more bloody stools as well as clots. He is pale, orthostatic, and tachycardic. NG aspirated are bilious. After resusc is begun, which of the following is the most appropriate initial test?
A. Angiography B. Nuclear medicine RBC scan C. Rigid proctoscopy D. Colonoscopy E. Barium Enema
C
All tests may play a role in evaluating a patient with massive loss of blood through the rectum, hematochezia protoscopy is the most appropriate initial test. Proctoscopy may reveal an anorectal source of the bleeding and a diffuse mucosal process, such as ulcerative proctitis.
Barium obscures details if angiography is subsequently needed. Furthermore, finding sigmoid diverticula does not prove that they are the souce of the bleeding. Mesenteric angio is performed if the hemorrhage is brisk and persistent. Bleeding rate of 1-5 cc/min is necessary to visualize the vessel. SMA should be injected first b/c most bleeding originates in the R colon. If no abnormalities, injecting IMA and finally celiac axis. If a should of bleeding is found, embolization may be performed with Gelfoam strips. coils or autologous blood clots. Rebleeding following occurs in 25%. Embolizatoin may occlude >1 bleeding vessel and lead to ischemia and even colonic infarction (5%). Embolization reserved for patients who cannot tolerate surgery or vasopressin.
Vasopressin may be selectively infuesed unto the mesenteric vessel. Even though it stops the bleeding in many patients, it may also cause cardiac arrhythmias, heart failure and HTN. Cessation may precipitate further bleeding in 30%. Use gives physician time to complete the resuscitation and address coexisting medical disorders
Sulfur colloid nuclear scanning’s isotope is cleared rapidly by the reticuloendothelial a and prepepitive scanning is not possible. RBCS may be tagged with technetium. detects bleeding at a rate as low as 0.1 mL/mL. This isotope is not cleared from the vascular system as rapidly. Repeated scanning may be possible over an dextended period
Colonoscopy is a valuable diagnostic and therapeutic tool for stable patients, who are not bleeding much. No bowel cleansing is needed but the exam must be does by an experienced endoscopist . Angiodysplastic lesions can be carefully treated by endoscopy measures
RUSH–COLON
With regard to UC, which of the following statements is true?
A. In at least half of the patients, the entire colon is involves with skip areas
B. Characteristic histologic findings of crpypt abscesses is the sine qua non of UC and is not seen with other inflammatory bowel conditions
C. The disease is most commonly a chronic relapsing one, with an acute/fulminant course seen in only 10% to 15% of patients
D. Cancers arising in association with UC tend to be located in the rectum and sigmoid, similar to cancers not assoc wirh I
E. Histgologic demonstration of granulomas confirmed the dx
C
UC is usually limited to the mucosal and submucosal layers of the bowel. Rectum is almost always involved with continuous proximal spread to varying lengths of colon. The entire colon is involved in at least 1/2 the patients
Characteristic crypt abscesses, which contain infiltration of neutrophils and eosinophils, extend down into the bases of the crypts of Lieberkuhn and lamina propria. Although crypt abscesses may be seen with other inflammatory conditions of the colon, they are always present with UC and generally in greater number. In contrast to Crohn’s disease, in which the supply of goblet cells is preserved, the microscopic appearance of UC characteristically reveals goblet cell depletion. UC is most commonly chronic and relapsing in character, although in 10-15% the disease runs an acute and fulminant course.
Cancers assoc with UC are usually dx later in their course b/c the S &S may be confused initially with an inflammatory relapse. For this reason, these cancers are assoc with a poorer prognosis. Studies have shown that contrary to what is believed, colitic cancers do not behave more aggressively than noncolitic counterparts. When compared with noncolitic cases, cancers arising within a colitic colon are more evenly distributed throughout the colon, have a higher incidence of proximal involvment and are frequently multiple. Granulomas found on histopathologic analysis are pathognomonic for Crohn’s disease and are not usually seen in patients with UC.
RUSH–COLON
39M with hx of mild long standing UC controlled with sulfasalazine recently underwent routine colonoscopy that shows a lesion in the sigmoid colon. Pathologic evaluation reveals high grade dysplasia. Which of the following is the best surgical option?
A. Sigmoid colectomy, provided that rectum is minimally involved
B. Proctocolectomy, construction of an ileal reservoir and ileoanal anastomosis
C. Proctocolectomy with continent ileostomy (Koch pouch)
D. Total proctocolectomy with Brooke ileostomy
E. Polypectomy to reduce the risks assoc with major abdo surgery
B
Proctocolectomy with permanent end ileostomy is an acceptable operation however, healthy, motivated patients who require surgery for UC may be eligible for a sphincter-preserving procedure. Options include abdominal colectomy with ileorectal anast, total proctocolectomy with continent ileostomy (Koch pouch) or the ileal pouch-anal anastomosis procedure. Ileorectal anast does not eradicate the disease or mucosa at risk for malignant transformation. The continent ileostomy procedure may require revision surgery at a future date b/c of slippage of the nipple valve and is not considered the best operation for a patient with an intact, normally functioning sphincter. The combo of protocolectomy, ileal reservoir (J pouch) and ileoanal anast offers the advantage of the diseased mucosa and the need for a permanent stoma being eliminated. Pouch may be a S or J shaped, which increases intestinal storage capacity and decr stool freq. A temporary diverting ileostomy is usually required for 2-3 months while the pouch heals. Recommended for select patients with UC and those with FAP. Not indicated for Crohn’s disease b/c of risk of recurrence within the pouch, which 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 with a permanent ileostomy. Similarly, ileoanal anast should be avoided in patients with pre-existing fecal incontinence from anorectal surgery or obstetric injuries. For appropriately selected patients, the functional results are good, with preservation of autonomic innervation to the bladder and genitalia. Fecal sensation and continence are retained in most of these patients.
The patient requires surgery b/c of dysplasia; total removal of mucosa at risk is essential. Polypectomy or segmental colectomy is not appropriate
RUSH–COLON
25F hx of repeated episodes of bloody diarrhea and general abdo cramping along with lower abdo pain and wt loss. The presumed dx is UC. Which of the following is the correct mgmt?
A. Barium enema radiographic exam is done early to assess the extent and severity of disease
B. Hydrocortisone has been shown to induce remissions but such steroid induced remissions are more likely than spontaneous remissions to be followed by a relapse
C. TPN if administered early as a part of the tx, may delay or even prevent the need for colectomy
D. Maintenance, low dose steroids are effective in preventing relapse
E. If medical therapy fails and abdo colectomy with an ileorectal anastomosis is performed, there is a 15-20% chance that carcinoma will develop in the rectal remnany during the next 30 yrs
E
Endoscopy w/bx is the most widely used method for dx’ing UC. Barium enema exams can be performed but should be done with caution and avoided during acute attacks b/c of risk for perforation and precipitation of toxic megacolon.
Prednisone or hydrocortisone is highly effective in tx acute phases of the illness. However, both drugs have side effects sufficiently adverse that the dose is tapered early when possible. Administration of low dose steroids on a maintenance basis has not been shown to prevent relapses. Risk for relapse is same whether it follows a steroid induced remission or a spontaneous remission.
Optimal role for TPN in the tx of these patients has not been well defined but it does not appear to delay the need for surgical intervention. It should not be used as a primary tx
Infliximab is used in patients with Crohn’s but it is also used in moderate-severe UC and an inadequate response to steroids. It is a anti TNF alha antibody that blocks the TNF alpha receptor, which in turn decreases inflammation. In general, it reduces S&S and maintains remission
Cancer developed in ~5-6% of patients with UC. Patients with pancolitis or disease of long standing duration are at highest risk. When an ileorectal anastomosis is performed, lifetime proctoscopic surveillance for dysplasia or neoplasia is mandatory b/c the risk for subsequent cancer is ~20% after 25 yrs. In addition to the risk of cancer, proctitis symptomatic enough to require proctectomy is another concern following ileorectostomy for UC. ~50% of patinet undergoing this operation require proctectomy b/c of cancer, dysplastic changes or refractory proctitis.
