PART II
Specific Considerations
CHAPTER 29
Colon, Rectum, and Anus
BASIC SCIENCE QUESTIONS
1. Which of the following is a branch of the inferior mesenteric artery?
A. Middle colic artery
B. Ileocolic artery
C. Sigmoidal arteries
D. Right colic artery
Answer: C
The arterial supply to the colon is highly variable (Fig. 29-1). In general, the superior mesenteric artery branches into the ileocolic artery (absent in up to 20% of people), which supplies blood flow to the terminal ileum and proximal ascending colon, the right colic artery, which supplies the ascending colon, and the middle colic artery, which supplies the transverse colon. The inferior mesenteric arterybranches into the left colic artery, which supplies the descending colon, several sigmoidal branches, which supply the sigmoid colon, and the superior rectal artery, which supplies the proximal rectum. The terminal branches of each artery form anastomoses with the terminal branches of the adjacent artery and communicate via the marginal artery of Drummond. This arcade is complete in only 15 to 20% of people. (See Schwartz 9th ed., p 1018.)
FIG. 29-1. Arterial blood supply to the colon.
2. Bacteria make up what percentage of the dry weight of feces?
A. 10%
B. 30%
C. 50%
D. 70%
Answer: B
Approximately 30% of fecal dry weight is composed of bacteria (1011 to 1012 bacteria/g of feces). Anaerobes are the predominant class of microorganism, and Bacteroides species are the most common (1011 to 1012 organisms/mL). Escherichia coli are the most numerous aerobes (108 to 1010 organisms/mL). (See Schwartz 9th ed., p 1019.)
3. Which of the following is associated with colorectal carcinoma?
A. Activation of the K-ras gene
B. Activation of APC
C. Activation of DCC (deleted in colorectal carcinoma)
D. Activation of p53
Answer: A
Over the past two decades, an intense research effort has focused on elucidating the genetic defects and molecular abnormalities associated with the development and progression of colorectal adenomas and carcinoma. Mutations may cause activation of oncogenes (K-ras) and/or inactivation of tumor-suppressor genes [APC, DCC (deleted in colorectal carcinoma), p53]. Colorectal carcinoma is thought to develop from adenomatous polyps by accumulation of these mutations (Fig. 29-2). (See Schwartz 9th ed., p 1041.)
FIG. 29-2. Schematic showing progression from normal colonic epithelium to carcinoma of the colon.
4. Deletion in the tumor suppressor phosphatase and tensin homolog (PTEN) is associated with all of the following EXCEPT
A. Familial adenomatous polyposis
B. Peutz-Jeghers syndrome
C. Juvenile polyposis
D. Cowden syndrome
Answer: A
Deletion of the tumor suppressor phosphatase and tensin homolog (PTEN) appears to be involved in a number of hamartomatous polyposis syndromes. Deletions in PTEN have been identified in juvenile polyposis, Peutz-Jeghers syndrome, Cowden syndrome, and PTEN-hamartoma syndrome, in addition to multiple endocrine neoplasia IIB. (See Schwartz 9th ed., p 1042.)
5. Which of the following is important in maintaining the integrity of the colonic mucosa?
A. Short-chain fatty acids
B. Alanine
C. Medium-chain fatty acids
D. Glutamine
Answer: A
Short-chain fatty acids (acetate, butyrate, and propionate) are produced by bacterial fermentation of dietary carbohydrates. Short-chain fatty acids are an important source of energy for the colonic mucosa, and metabolism by colonocytes provides energy for processes such as active transport of sodium. Lack of a dietary source for production of short-chain fatty acids, or diversion of the fecal stream by an ileostomy or colostomy, may result in mucosal atrophy and diversion colitis. (See Schwartz 9th ed., p 1019.)
6. The parasympathetic innervations to the transverse colon are from
A. T6-T12
B. L1-L3
C. S2-S4
D. The vagus nerve
Answer: D
The colon is innervated by both sympathetic (inhibitory) and parasympathetic (stimulatory) nerves, which parallel the course of the arteries. Sympathetic nerves arise from T6–T12 and L1–L3. The parasympathetic innervation to the right and transverse colon is from the vagus nerve; the parasympathetic nerves to the left colon arise from sacral nerves S2–S4 to form the nervi erigentes. (See Schwartz 9th ed., p 1018.)
7. The origin of the middle rectal artery is the
A. Inferior mesenteric artery
B. Iliac artery
C. Internal pudendal artery
D. Inferior epigastric artery
Answer: B
The superior rectal artery arises from the terminal branch of the inferior mesenteric artery and supplies the upper rectum. The middle rectal artery arises from the internal iliac; the presence and size of these arteries are highly variable. The inferior rectal artery arises from the internal pudendal artery, which is a branch of the internal iliac artery. A rich network of collaterals connects the terminal arterioles of each of these arteries, thus making the rectum relatively resistant to ischemia (Fig. 29-3). (See Schwartz 9th ed., p 1018.)
FIG. 29-3. Arterial supply to the rectum and anal canal.
8. Colorectal cancers which develop from defects in the RER (replication error repair) pathway when compared to tumors which develop from the LOH (loss of heterozygosity) pathway
A. Occur more commonly in the left colon
B. Have a worse prognosis
C. Possess diploid DNA
D. Express microsatellite instability
Answer: D
The RER pathway is associated with microsatellite instability (MSI). Microsatellites are regions of the genome in which short base-pair segments are repeated several times. These areas are particularly prone to RER. Consequently, a mutation in a mismatch repair gene produces variable lengths of these repetitive sequences, a finding that has been described as microsatellite instability. Approximately 15% of colorectal cancers are associated with MSI.
Tumors associated with MSI appear to have different biologic characteristics than do tumors that result from the LOH pathway. Tumors with MSI are more likely to be right sided, possess diploid DNA, and are associated with a better prognosis than tumors that arise from the LOH pathway that are microsatellite stable. Tumors arising from the LOH pathway tend to occur in the more distal colon, often have chromosomal aneuploidy, and are associated with a poorer prognosis. (See Schwartz 9th ed., p 1042.)
9. Extensive perianal condyloma accuminata is best treated with
A. Topical steroids
B. Topical podophyllin
C. Topical imiquimod
D. Surgical resection and fulguration
Answer: D
Treatment of anal condyloma depends on the location and extent of disease. Small warts on the perianal skin and distal anal canal may be treated in the office with topical application of bichloracetic acid or podophyllin. Although 60 to 80% of patients will respond to these agents, recurrence and reinfection are common. Imiquimod (Aldara) is an immunomodulator that recently was introduced for topical treatment of several viral infections, including anogenital condyloma. Initial reports suggest that this agent is highly effective in treating condyloma located on the perianal skin and distal anal canal. Larger and/or more numerous warts require excision and/or fulguration in the operating room. Excised warts should be sent for pathologic examination to rule out dysplasia or malignancy. It is important to note that prior use of podophyllin may induce histologic changes that mimic dysplasia. (See Schwartz 9th ed., p 1067.)
CLINICAL QUESTIONS
1. Which of the following manometric findings indicates dysfunction of the internal sphincter?
A. Resting pressure 20 mmHg
B. Squeeze pressure 60 mmHg
C. High pressure zone 2 cm
D. Presence of a rectoanal inhibitory reflex
Answer: A
The resting pressure in the anal canal reflects the function of the internal anal sphincter (normal: 40 to 80 mmHg), while the squeeze pressure, defined as the maximum voluntary contraction pressure minus the resting pressure, reflects function of the external anal sphincter (normal: 40 to 80 mmHg above resting pressure). The high-pressure zone estimates the length of the anal canal (normal: 2.0 to 4.0 cm). The rectoanal inhibitory reflex can be detected by inflating a balloon in the distal rectum; absence of this reflex is characteristic of Hirschsprung’s disease. (See Schwartz 9th ed., p 1021.)
2. The treatment of choice for acute anal fissures is
A. Excision and primary closure
B. Lateral internal sphincterotomy
C. Botulinum injection
D. Laxatives and sitz baths
Answer: D
Therapy for an acute anal fissure focuses on breaking the cycle of pain, spasm, and ischemia thought responsible for development of fissure in ano. First-line therapy to minimize anal trauma includes bulk agents, stool softeners, and warm sitz baths. The addition of 2% lidocaine jelly or other analgesic creams can provide additional symptomatic relief. Botulinum toxin (Botox) causes temporary muscle paralysis by preventing acetylcholine release from presynaptic nerve terminals. Injection of botulinum toxin is used in some centers as an alternative to surgical sphincterotomy for chronic fissure. Surgical therapy traditionally has been recommended for chronic fissures that have failed medical therapy, and lateral internal sphincterotomy is the procedure of choice for most surgeons. (See Schwartz 9th ed., p 1060.)
3. A patient with obstipation and abdominal distention presents to the emergency room. Based on the results of the contrast enema shown in Fig. 29-4, the next step in management should be
A. NG suction, bowel rest, and observation
B. Enemas until the obstruction is relieved
C. Proctoscopy
D. Exploratory laparotomy
Answer: C
Sigmoid volvulus often can be differentiated from cecal or transversecolon volvulus by the appearance of plain x-rays of the abdomen. Sigmoid volvulus produces a characteristic bent inner tube or coffee bean appearance, with the convexity of the loop lying in the right upper quadrant (opposite the site of obstruction). Gastrografin enema shows a narrowing at the site of the volvulus and a pathognomonicbird’s beak (See Fig. 29-4.).
Unless there are obvious signs of gangrene or peritonitis, the initial management of sigmoid volvulus is resuscitation followed by endoscopic detorsion. Detorsion is usually most easily accomplished by using a rigid proctoscope, but a flexible sigmoidoscope or colonoscope might also be effective. (See Schwartz 9th ed., p 1055.)
FIG. 29-4. Sigmoid volvulus: Gastrografin enema showing “bird-beak” sign (arrow). (Reproduced with permission from Nivatvongs S, Becker ER: Colon, rectum and anal canal, in James EC, Corry RJ, Perry JCF Jr. (eds): Basic Surgical Practice. Philadelphia: Hanley & Belfus, 1987. Copyright © Elsevier.)
4. Elective proctocolectomy should be advised for which of the following patients with ulcerative colitis?
A. Low-grade dysplasia on biopsy
B. Moderate dysplasia on biopsy
C. Pancolonic disease for >20 years, independent of biopsy results
D. All of the above
Answer: D
Although low-grade dysplasia was long thought to represent minimal risk, more recent studies show that invasive cancer may be present in up to 20% of patients with low-grade dysplasia. For this reason, any patient with dysplasia should be advised to undergo proctocolectomy. Controversy exists over whether prophylactic proctocolectomy should be recommended for patients who have had chronic ulcerative colitis for >10 years in the absence of dysplasia. Proponents of this approach note that surveillance colonoscopy with multiple biopsies samples only a small fraction of the colonic mucosa and dysplasia and carcinoma are often missed. Opponents cite the relatively low risk of progression to carcinoma if all biopsies have lacked dysplasia (approximately 2.4%). Neither approach has been definitively shown to decrease mortality from colorectal cancer.
Risk of malignancy increases with pancolonic disease and the duration of symptoms is approximately 2% after 10 years, 8% after 20 years, and 18% after 30 years. (See Schwartz 9th ed., p 1035.)
5. In order to avoid complications, output from an ileostomy should be kept below
A. 500 mL/day
B. 1000 mL/day
C. 1500 mL/day
D. 2000 mL/day
Answer: C
The creation of an ileostomy bypasses the fluid absorbing capability of the colon, and dehydration with fluid and electrolyte abnormalities is not uncommon. Ideally, ileostomy output should be maintained at less than 1500 mL/d to avoid this problem. Bulk agents and opioids (Lomotil, Imodium, tincture of opium) are useful. The somatostatin analogue, Octreotide, has been used with variable success in this setting. (See Schwartz 9th ed., p 1031.)
6. An internal hemorrhoid that prolapses past the dentate line with straining is a
A. First-degree hemorrhoid
B. Second-degree hemorrhoid
C. Third-degree hemorrhoid
D. Fourth-degree hemorrhoid
Answer: A
Internal hemorrhoids are located proximal to the dentate line and covered by insensate anorectal mucosa. Internal hemorrhoids may prolapse or bleed, but rarely become painful unless they develop thrombosis and necrosis (usually related to severe prolapse, incarceration, and/or strangulation). Internal hemorrhoids are graded according to the extent of prolapse. First-degree hemorrhoids bulge into the anal canal and may prolapse beyond the dentate line on straining. Second-degree hemorrhoids prolapse through the anus but reduce spontaneously. Third-degree hemorrhoids prolapse through the anal canal and require manual reduction. Fourth-degree hemorrhoids prolapse but cannot be reduced and are at risk for strangulation. (See Schwartz 9th ed., p 1058.)
7. In patients with inflammatory bowel disease, erythema nodosum
A. Is seen more commonly in men
B. May occur near a stoma
C. Usually occurs on the lower legs
D. All of the above
Answer: C
Erythema nodosum is seen in 5 to 15% of patients with inflammatory bowel disease and usually coincides with clinical disease activity. Women are affected three to four times more frequently than men. The characteristic lesions are raised, red, and predominantly on the lower legs. Pyoderma gangrenosum is an uncommon but serious condition that occurs almost exclusively in patients with inflammatory bowel disease. The lesion begins as an erythematous plaque, papule, or bleb, usually located on the pretibial region of the leg and occasionally near a stoma. The lesions progress and ulcerate, leading to a painful, necrotic wound. Pyoderma gangrenosum may respond to resection of the affected bowel in some patients. In others, this disorder is unaffected by treatment of the underlying bowel disease. (See Schwartz 9th ed., p 1034.)
8. Lymphoma of the colon is most commonly found in the
A. Cecum
B. Transverse colon
C. Sigmoid colon
D. Rectum
Answer: A
Lymphoma involving the colon and rectum is rare, but accounts for about 10% of all GI lymphomas. The cecum is most often involved, probably as a result of spread from the terminal ileum. Symptoms include bleeding and obstruction, and these tumors may be clinically indistinguishable from adenocarcinomas. Bowel resection is the treatment of choice for isolated colorectal lymphoma. Adjuvant therapy may be given based upon the stage of disease. (See Schwartz 9th ed., p 1052.)
9. Which of the following is the first test that should be performed in a patient with lower gastrointestinal bleeding?
A. Nasogastric aspiration
B. Anoscopy
C. Proctoscopy
D. Colonoscopy
Answer: A
Because the most common source of GI hemorrhage is esophageal, gastric, or duodenal, nasogastric aspiration should always be performed; return of bile suggests that the source of bleeding is distal to the ligament of Treitz. If aspiration reveals blood or nonbile secretions, or if symptoms suggest an upper intestinal source, esophagogastroduodenoscopy is performed. Anoscopy and/or limited proctoscopy can identify hemorrhoidal bleeding. If the patient is hemodynamically stable, a rapid bowel preparation (over 4 to 6 hours) can be performed to allow colonoscopy. (See Schwartz 9th ed., p 1022.)
10. In a patient with inflammatory colitis, which of the following would suggest the diagnosis of Crohn’s colitis?
A. Ileitis
B. Crypt abscesses
C. Rectal sparing
D. Proctitis
Answer: C
Although ulcerative colitis and Crohn’s colitis share many pathologic and clinical similarities, these conditions may be differentiated in 85% of patients. 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 fore-shortened and the mucosa replaced by scar. In quiescent ulcerative colitis, the colonic mucosa may appear normal endoscopically and microscopically. Ulcerative colitis may affect the rectum (proctitis), rectum and sigmoid colon (proctosigmoiditis), rectum and left colon (left-sided colitis), or the rectum and entire colon (pancolitis). 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’s disease. (See Schwartz 9th ed., p 1034.)
11. Which of the following is the procedure of choice for a patient with Crohn’s colitis involving the left colon who has rectal sparing?
A. Left colectomy with primary anastomosis
B. Left colectomy with colostomy
C. Total colectomy with primary anastomosis
D. Total colectomy with ileostomy
Answer: A
Unlike ulcerative colitis, Crohn’s colitis may be segmental and rectal sparing often is observed. A segmental colectomy may be appropriate if the remaining colon and/or rectum appear normal. An isolated colonic stricture also may be treated by segmental colectomy. (See Schwartz 9th ed., p 1037.)
12. Approximately 5% of patients with complicated diverticulitis develop a fistula to an adjacent organ. The most commonly involved organ is
A. Small bowel
B. Skin
C. Bladder
D. Vagina
Answer: C
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 coloentericfistulas. Colocutaneous fistulas are a rare complication of diverticulitis. (See Schwartz 9th ed., p 1040.)
13. Azathioprine (which can be used in the treatment of inflammatory bowel disease)
A. Decreases the efficacy of leucocytes
B. Can be used instead of steroids in patients who are steroid refractory
C. Has an onset of action of 6-12 weeks
D. Requires intravenous administration
Answer: C
Azathioprine and 6-mercaptopurine 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’s disease in patients who have failed salicylate therapy or who are dependent upon or refractory to corticosteroids. It is important to note, however, that the onset of action of these drugs takes 6 to 12 weeks, and concomitant use of corticosteroids almost always is required. (See Schwartz 9th ed., p 1035.)
14. The most common infectious cause for emergency laparotomy in a patient with AIDS is
A. Cytomegalovirus
B. Toxoplasmosis
C. Salmonella
D. Herpes simplex
Answer: A
Opportunistic infections with bacteria (Salmonella, Shigella, Campylobacter, Chlamydia, and Mycobacterium species), fungi (Histoplasmosis, Coccidiosis, Cryptococcus), protozoa (Toxoplasmosis,Cryptosporidiosis, Isosporiasis), and viruses (CMV, herpes simplex virus) can cause diarrhea, abdominal pain, and weight loss. CMV in particular may cause severe enterocolitis and is the most common infectious cause of emergency laparotomy in AIDS patients. C. difficile colitis is a major concern in these patients, especially because many patients are maintained on suppressive antibiotic therapy. (See Schwartz 9th ed., p 1070.)
15. A microscopic focus of cancer is found in a polyp after endoscopic resection. Which of the following is an indication for colectomy in this patient?
A. Focus of cancer 2 mm from the resection margin
B. Polyp size >2 cm
C. Lymphovascular invasion
D. History of multiple polyps
Answer: C
Occasionally, a polyp that was thought to be benign will be found to harbor invasive carcinoma after polypectomy. Treatment of a malignant polyp is based upon the risk of local recurrence and the risk of lymph node metastasis. The risk of lymph node metastases depends primarily upon the depth of invasion. Invasive carcinoma in the head of a pedunculated polyp with no stalk involvement carries a low risk of metastasis (1%) and may be completely resected endoscopically. However, lymphovascular invasion, poorly differentiated histology, or tumor within 1 mm of the resection margin greatly increases the risk of local recurrence and metastatic spread. Segmental colectomy is then indicated. Invasive carcinoma arising in a sessile polyp extends into the submucosa and is usually best treated with segmental colectomy (Fig. 29-5). (See Schwartz 9th ed., p 1048.)
FIG. 29-5. Levels of invasive carcinoma in pedunculated and sessile polyps. ca = carcinoma.
16. The risk of cancer is highest in
A. Tubular adenomas
B. Villous adenomas
C. Tubulovillous adenomas
D. Hamartomatous adenomas
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%). (See Schwartz 9th ed., p 1042.)
In contrast to adenomatous polyps, hamartomatous polyps (juvenile polyps) usually are not premalignant. (See Schwartz 9th ed., p 1042.)
17. Which of the following is often effective in the treatment of a desmoid tumor of the mesentery in a patient with familial adenomatous polyposis?
A. Tamoxifen
B. Methotrexate
C. Steroids
D. Radiotherapy
Answer: A
Desmoid tumors in particular can make surgical management difficult and are a source of major morbidity and mortality in patients with FAP. Desmoid tumors are often hormone responsive and growth may be inhibited in some patients with tamoxifen. COX-2 inhibitors and NSAIDs also may be beneficial in this setting. (See Schwartz 9th ed., p 1044.)
18. Treatment of Ogilvie’s syndrome includes
A. Proctoscopy
B. Sigmoid colectomy
C. Intravenous neostigmine
D. Saline enemas
Answer: C
Colonic pseudo-obstruction (Ogilvie’s syndrome) is a functional disorder in which the colon becomes massively dilated in the absence of mechanical obstruction. Initial treatment consists of cessation of narcotics, anticholinergics, or other medications that may contribute to ileus. Strict bowel rest and IV hydration are crucial. Most patients will respond to these measures. In patients who fail to improve, colonoscopic decompression often is effective. However, this procedure is technically challenging and great care must be taken to avoid causing perforation. Recurrence occurs in up to 40% of patients. IV neostigmine (an acetylcholinesterase inhibitor) also is extremely effective in decompressing the dilated colon and is associated with a low rate of recurrence (20%). However, neostigmine may produce transient but profound bradycardia and may be inappropriate in patients with cardiopulmonary disease. Because the colonic dilatation typically is greatest in the proximal colon, placement of a rectal tube is rarely effective. (See Schwartz 9th ed., p 1056.)
19. Which of the following has the lowest recurrence rate after reduction and repair of a rectal prolapse?
A. Perineal reefing of the rectal mucosa (Delorme procedure)
B. Abdominal rectopexy (Ripstein procedure)
C. Perineal rectosigmoidectomy (Altemeier procedure)
D. Reduction of the perineal hernia and closure of the cul-de-sac (Moschcowitz procedure)
Answer: B
The primary therapy for rectal prolapse is surgery, and more than 100 different procedures have been described to treat this condition. Operations can be categorized as either abdominal or perineal. Abdominal operations have taken three major approaches: (a) reduction of the perineal hernia and closure of the cul-de-sac (Moschcowitz’s operation); (b) fixation of the rectum, either with a prosthetic sling (Ripstein and Wells rectopexy) or by suture rectopexy; or (c) resection of redundant sigmoid colon. In some cases, resection is combined with rectal fixation (resection rectopexy). Abdominal rectopexy with or without resection also is increasingly performed laparoscopically. Perineal approaches have focused on tightening the anus with a variety of prosthetic materials, reefing the rectal mucosa (Delorme procedure), or resecting the prolapsed bowel from the perineum (perineal rectosigmoidectomy or Altemeier procedure) (Fig. 29-6).
Because rectal prolapse occurs most commonly in elderly women, the choice of operation depends in part upon the patient’s overall medical condition. Abdominal rectopexy (with or without sigmoid resection) offers the most durable repair, with recurrence occurring in fewer than 10% of patients. Perineal rectosigmoidectomy avoids an abdominal operation and may be preferable in high-risk patients, but is associated with a higher recurrence rate. Reefing the rectal mucosa is effective for patients with limited prolapse. Anal encirclement procedures generally have been abandoned. (See Schwartz 9th ed., p 1054.)
FIG. 29-6. Transabdominal proctopexy for rectal prolapse. The fully mobilized rectum is sutured to the presacral fascia. A. Anterior view. B. Lateral view. If desired, a sigmoid colectomy can be performed concomitantly to resect the redundant colon.
20. A 2-cm invasive cancer of the toproximal transverse colon carcinoma should be treated with which of the following procedures?
A. Ileocecectomy
B. Ascending colectomy
C. Right hemicolectomy
D. Extended right hemicolectomy
Answer: D
Curative resection of a colorectal cancer usually is accomplished best by performing a proximal mesenteric vessel ligation and radical mesenteric clearance of the lymphatic drainage basin of the tumor site with concomitant resection of the overlying omentum (Fig. 29-7). (See Schwartz 9th ed., p 1024, and Fig. 29-8.)
FIG. 29-7. Terminology of types of colorectal resections: A→C Ileocecectomy; + A + B→D Ascending colectomy; + A + B→F Right hemicolectomy; + A + B→G Extended right hemicolectomy; + E + F→G + H Transverse colectomy; G→I Left hemicolectomy; F→I Extended left hemicolectomy; J + K Sigmoid colectomy; + A + B→J Subtotal colectomy; + A + B→K Total colectomy; + A + B→L Total proctocolectomy. (Reproduced with permission from Fielding LP, Gold berg SM (eds): Rob & Smith’s Operative: Surgery of the Colon, Rectum, and Anus. UK: Elsevier Science Ltd., 1993, p 349.)
FIG. 29-8. Extent of resection for carcinoma of the colon. A. Cecal cancer. B. Hepatic flexure cancer. C. Transverse colon cancer. D. Splenic flexure cancer. E. Descending colon cancer. F. Sigmoid colon cancer.
21. Which of the following is an extraintestinal manifestation of inflammatory bowel disease?
A. Hepatosteatosis
B. Primary sclerosing cholangitis
C. Pericholangitis
D. All of the above
Answer: D
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%. Fatty infiltration may be reversed by medical or surgical treatment of colonic disease, but cirrhosis is irreversible. 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. Colectomy will not reverse this disease, and the only effective therapy is liver transplantation. Pericholangitis also is 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.Patients who develop bile duct carcinoma in the presence of inflammatory bowel disease are, on average, 20 years younger than other patients with bile duct carcinoma. (See Schwartz 9th ed., p 1034.)
22. Anal fissures in Crohn’s disease are most commonly
A. Anterior
B. Posterior
C. Lateral
D. None of the aboveóthe distribution is equal
Answer: C
The most common perianal lesions in Crohn’s disease are skin tags that are minimally symptomatic. Fissures also are common. Typically, a fissure from Crohn’s disease is particularly deep or broad and perhaps better described as an anal ulcer. They often are 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’s disease. (See Schwartz 9th ed., p 1038.)
23. The risk of colon cancer in a patient who was diagnosed with ulcerative colitis 20 years ago is approximately
A. 8%
B. 18%
C. 28%
D. 38%
Answer: A
Risk of malignancy increases with pancolonic disease and the duration of symptoms is approximately 2% after 10 years, 8% after 20 years, and 18% after 30 years. Unlike sporadic colorectal cancers, carcinoma developing in the context of ulcerative colitis is more likely to arise from areas of flat dysplasia and may be difficult to diagnose at an early stage. (See Schwartz 9th ed., p 1036.)
24. The most common complication following hemorrhoidectomy is
A. Fecal impaction
B. Bleeding
C. Urinary retention
D. Infection
Answer: C
Urinary retention is a common complication following hemorrhoidectomy and occurs in 10 to 50% of patients. The risk of urinary retention can be minimized by limiting intraoperative and perioperative IV fluids, and by providing adequate analgesia. Pain also can lead to fecal impaction. Risk of impaction may be decreased by preoperative enemas or a limited mechanical bowel preparation, liberal use of laxatives postoperatively, and adequate pain control. Although a small amount of bleeding, especially with bowel movements, is to be expected, massive hemorrhage can occur after hemorrhoidectomy. Bleeding may occur in the immediate postoperative period (often in the recovery room) as a result of inadequate ligation of the vascular pedicle. This type of hemorrhage mandates an urgent return to the operating room where suture ligation of the bleeding vessel will often solve the problem. Bleeding may also occur 7 to 10 days after hemorrhoidectomy when the necrotic mucosa overlying the vascular pedicle sloughs. Although some of these patients may be safely observed, others will require an examination under anesthesia to ligate the bleeding vessel or to oversew the wounds if no specific site of bleeding is identified. Infection is uncommon after hemorrhoidectomy; however, necrotizing soft tissue infection can occur. (See Schwartz 9th ed., p 1059.)
25. A colorectal carcinoma that invades the submucosa and has two positive lymph nodes and no metastases is
A. Stage I
B. Stage II
C. Stage III
D. Stage IV
Answer: C
This is a T1, N1, M0 tumor, which makes it stage III. (See Schwartz 9th ed., p 1047, Tables 29-1 and 29-2.)
TABLE 29-1 TNM staging of colorectal carcinoma and 5-year survival
TABLE 29-2 TNM staging of colorectal carcinoma
26. Treatment of severe C. difficile proctosigmoiditis which is unresponsive to intravenous antibiotics may include
A. Saline enemas
B. Steroid enemas
C. Vancomycin enemas
D. Probiotic enemas
Answer: C
Management [of C. difficile colitis] should include immediate cessation of the offending antimicrobial agent. Patients with mild disease (diarrhea but no fever or abdominal pain) may be treated as outpatients with a 10-day course of oral metronidazole. Oral vancomycin is a second-line agent used in patients allergic to metronidazole or in patients with recurrent disease. More severe diarrhea associated with dehydration and/or fever and abdominal pain is best treated with bowel rest, IV hydration, and oral metronidazole or vancomycin. Proctosigmoiditis may respond to vancomycin enemas. Recurrent colitis occurs in up to 20% of patients and may be treated by a longer course of oral metronidazole or vancomycin (up to 1 month). Reintroduction of normal flora by ingestion of probiotics has been suggested as a possible treatment for recurrent or refractory disease. Fulminant colitis, characterized by septicemia and/or evidence of perforation, requires emergent laparotomy. A total abdominal colectomy with end ileostomy may be lifesaving. (See Schwartz 9th ed., p 1057.)
27. Which of the following is an extraintestinal manifestation of familial adenomatous polyposis?
A. Arthritis
B. Uveitis
C. Central nervous system tumors
D. Erythema nodosum
Answer: C
FAP may be associated with extraintestinal manifestations such as congenital hypertrophy of the retinal pigmented epithelium, desmoid tumors, epidermoid cysts, mandibular osteomas (Gardner’s syndrome), and central nervous system tumors (Turcot’s syndrome). (See Schwartz 9th ed., p 1044.)
28. Which of the following is characterized by hamartomas formed from all three embryonic layers?
A. Familial juvenile polyposis
B. Peutz-Jeghers syndrome
C. Cronkite-Canada syndrome
D. Cowden syndrome
Answer: D
Cowden syndrome is an autosomal dominant disorder with hamartomas of all three embryonal cell layers. Facial trichilemmomas, breast cancer, thyroid disease, and GI polyps are typical of the syndrome. Patients should be screened for cancers. Treatment is otherwise based upon symptoms. (See Schwartz 9th ed., p 1043.)
29. How many distinct layers of the rectal wall can be seen on endorectal ultrasound?
A. 2
B. 3
C. 4
D. 5
Answer: D
Endorectal ultrasound is primarily used to evaluate the depth of invasion of neoplastic lesions in the rectum. The normal rectal wall appears as a five-layer structure (Fig. 29-9). Ultrasound can reliably differentiate most benign polyps from invasive tumors based upon the integrity of the submucosal layer. Ultrasound also can differentiate superficial T1–T2 from deeper T3–T4 tumors. Overall, the accuracy of ultrasound in detecting depth of mural invasion ranges between 81 and 94%. This modality also can detect enlarged perirectal lymph nodes, which may suggest nodal metastases; accuracy of detection of pathologically positive lymph nodes is 58 to 83%. Ultrasound may also prove useful for early detection of local recurrence after surgery. (See Schwartz 9th ed., p 1020.)
FIG. 29-9. A. Schematic of the layers of the rectal wall observed on endorectal ultrasonography. B. Normal endorectal ultrasonography. (A. Courtesy of Charles O. Finne III, MD, Minneapolis, MN.)
30. The initial treatment of symptomatic pouchitis includes
A. Oral antibiotics
B. Intravenous antibiotics
C. Probiotic enemas
D. Steroid enemas
Answer: A
Pouchitis is an inflammatory condition that affects both ileoanal pouches and continent ileostomy reservoirs. 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’s disease. The etiology of pouchitis is unknown. Some believe pouchitis results from fecal stasis within the pouch but emptying studies are not confirmatory. Antibiotics (metronidazole ± ciprofloxacin) are the mainstays of therapy and most patients will respond rapidly to either oral preparations or enemas. Some patients develop chronic pouchitis that necessitates ongoing suppressive antibiotic therapy. Salicylate and corticosteroid enemas also have been used with some success. Reintroduction of normal flora by ingestion of probiotics has been suggested as a possible treatment in refractory cases. Occasionally, pouch excision is necessary to control the symptoms of chronic pouchitis. (See Schwartz 9th ed., p 1032.)