General Surgery (Board Review Series) 1st Edition

14

Colon, Rectum, and Anus

James W. Thiele

1. Anatomic Considerations
2. Anatomy of the colon
3. The colon is dividedinto the cecum and the ascending, transverse, descending, and sigmoid colon.
4. The cecum

• is the first and largest segment (7.5 cm to 8.5 cm) of the colon.
• is the most common site of colonic rupturebecause it has the largest radius and most wall tension for a given pressure.
• The ileum joins on its posteromedial border and the appendix is attached just below the ileocecal valve.

1. The colonic wall

• is composed of mucosa, submucosa, inner circular muscle, outer longitudinal muscle, and serosa.

1. Teniae coli

• are three longitudinal muscular bands that converge proximally on the appendix and continue to the proximal rectum.

1. Haustra

• are sacculations between the teniae that are divided by plicae semilunaris.

2. Blood supply of the colon
3. Arterial supply (Figure 14-1)
4. The superior mesenteric artery

• branches into the ileocolic, right colic, and middle colic branches to supply the colon from the cecum to the splenic flexure.

2. The inferior mesenteric artery

• branches into the left colic, sigmoidal, and superior rectal branches to supply the descending and sigmoid colon and the upper rectum.

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3. The arc of Riolan

• provides collateral blood flow between the inferiorand superior mesenteric arteries.

Figure 14-1. Arterial blood supply of the colon. The Arc of Riolan is the principle vessel that provides collateral blood flow between the superior and inferior mesenteric arteries. The splenic flexure is the watershed area of the colon, having distal blood supply from both of the mesenteric arteries. It is a common area of ischemia in states of low flow to the colon. (Reprinted with permission from Nora PF: Operative Surgery: Principles and Techniques, 3rd ed. Philadelphia, WB Saunders, p 613.)

1. Venous drainage

• of the colon and rectum is via the superior and inferior mesenteric veins, which parallel the arterial supply.

1. The inferior mesenteric veindrains into the splenic vein.
2. The superior mesenteric veinjoins the splenic vein to form the portal vein.
3. Lymphatic drainage
4. Lymph channelsare located in the submucosa and muscularis mucosa, but not in the mucosa.

• Thus, mucosal cancers rarely metastasize.

1. Lymph vesselsparallel the arterial supply of the colon.

• Nodes are located in the wall of the colon (epicolic), along the inner margin (paracolic), near mesenteric vessels (intermediate), or around the main mesenteric arteries (main).

1. Anatomy of the rectum
2. The rectum extendsfrom the sigmoid colon to the anal canal.
3. The proximal rectum

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• is identified by the merging of the teniae coli into a single circumferential layer of longitudinal muscle.

1. The peritoneum

• covers the upper third of the rectumon the anterior and lateral surfaces and the middle third on the anterior surface only.
• The lower third of the rectum is below the peritoneal reflection.

1. Fascia
2. Denonvillier's fascia(anterior)

• is the rectovesical fascia in men and the rectovaginal fascia in women.

2. Waldeyer's fascia(posterior)

• is the rectosacral fascia in both genders.

Figure 14-2. (A) Arterial supply and (B) venous drainage of the rectum. (Reprinted with permission from Schwartz S: Principles of Surgery, 7th ed. New York, McGraw-Hill, 1998, p 1270.)

2. Blood supply and drainage of the rectum(Figure 14-2)
3. Arterial supply
4. The superior rectal branchof the inferior mesenteric artery and the middle rectal branch of the internal iliac artery supply the upper two thirds of the rectum and have collaterals between them.
5. The inferior rectal branchof the pudendal artery supplies the

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lower third of the rectum and provides collaterals to the upper rectum.

1. Venous drainage
2. The upper two thirds

• is drained by the superior and middle rectal veins, which empty into the portal system via the inferior mesenteric vein.

1. The lower third of the rectum

• is drained by the inferior rectal vein, which empties into the caval system via the internal iliac veins.

3. Lymphatic drainage of the rectum
4. The upper two thirds of the rectum drains into the inferior mesenteric nodes.
5. The lower third of the rectum primarily drains into the inferior mesenteric nodesas well but can also drain via alternate routes into the iliac nodes and subsequently into the periaortic lymph nodes.
6. General anatomy of the anal canal
7. The anal canal

• extends from the levator ani muscle (pelvic diaphragm) to the anal verge.
• contains the dentate line, which is the squamocolumnar junctionbetween the rectum and anus.
• is surrounded by a muscular sphincter.

1. The internal sphincter

• is smooth muscleand is contracted at rest.
• is a continuation of the inner circular muscle of the rectum.
• Activation of sympathetic and parasympatheticnerves causes relaxation of this sphincter.

1. The external sphincter

• is voluntary, striated muscle divided into subcutaneous, superficial, and deep portions.
• is a continuation of the levator ani muscle.
• Innervationis via the inferior rectal branch of the pudendal nerve and the perineal branch of the fourth sacral nerve.

2. Arterial supply and venous drainage of the anus

. Arterial supply is via the inferior rectal artery.

1. Venous drainageabove the dentate line is via the submucosal internal hemorrhoidal plexus, while that below the dentate line is via the communicating external hemorrhoidal plexus.
2. Benign Lesions of the Colon and Rectum
3. Adenomatous polyps

• are benign lesions with significant malignant potential.

1. Tubular adenomas

• constitute 60% to 80% of adenomatous polyps and are generally small, pedunculated masses with a branching, glandular histologic appearance.

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1. The overall incidence of carcinoma in these polyps is 15%.
2. Increasing size results in an increased incidence of cancer.
3. Villous adenomas

• tend to occur more distally in the colon and are usually sessile with long, finger-like glandular projections.
• These polyps are generally largerthan tubular adenomas and have a greater propensity for malignant change.

3. Tubulovillous adenomas

• have characteristics of both types of polyps and the degree of malignant potential is directly related to the percentage of the villous component.

1. Benign lesions without malignant potential
2. Hyperplastic polyps

• are smooth, rounded, usually sessile lesions found most frequently in the distal colon.
• are not premalignant and usually remain small or regress.
• These lesions may be indistinguishable from adenomas grossly.

2. Inflammatory polyps

• are benign lesions that arise in response to mucosal injury (e.g., ulcerative colitis).

3. Juvenile polyps or hamartomatous polyps

• are benign lesions frequently found throughout the entire gastrointestinal tract.
• may be a source of gastrointestinal bleeding.
• Peutz-Jeghers syndromeis an autosomal dominant syndrome associated with multiple hamartomatous polyps in addition to melanin deposits in the buccal mucosa, lips, nose, palms, and feet.

1. Treatment of colonic polyps
2. Adenomatous polyps

• are treated with colonoscopic resectionwith pathologic examination for foci of carcinoma.

1. For completely resected lesions, follow-up colonoscopy is performed in 3 to 5 years.
2. Incompletely resected lesions or lesions too large for colonoscopic resection generally require surgical resection of the affected colon.
3. Asymptomatic hyperplastic, inflammatory, and juvenile polypsgenerally do not require additional surveillance or therapy.

III. Malignant Neoplasms of the Colon and Rectum

1. Adenocarcinoma of the colon
2. Risk factors
3. Genetic predisposition

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1. Nonpolyposis inherited colon cancer (Lynch syndrome)

• is characterized by right-sided colon cancerin young patients without multiple polyps.

2. Lynch syndrome I is only associated with colon cancer.
3. Lynch syndrome II (family cancer syndrome) is associated with colorectal, endometrial, gastric, and other types of cancers.
4. Both are autosomal dominant, linked to chromosome 18.
5. Familial adenomatous polyposis syndromes

• are characterized by multiple colonic polyps occurring by age 30.
• exhibit autosomal dominantinheritance.

2. Phenotypic subtypes include familial polyposis coli, Gardner's syndrome(epidermal inclusion cysts, colonic polyps, and osteomas), and Turcot syndrome (colonic polyps and brain tumors).
3. Chromosome 5 near q21locus is the adenomatous polyposis coli (APC) gene.
4. Many familial colon cancers

• are not associated with a well-defined genetic lesion as described with the above syndromes.

1. A high-fat dietis a significant risk factor.

• Protective factorsmay include aspirin, selenium, thioesters, carotenoids, and high fiber.

1. Long-standing ulcerative colitisis also a significant risk factor.
2. Screening and diagnostic techniques
3. Current screening techniques

• have generally not been shown to improve overall survival.

1. The American Cancer Society's current recommendationsfor screening in low-risk, asymptomatic individuals include:
2. Digital rectal examination(DRE) and testing for occult blood annually beginning at age 40.
3. Flexible sigmoidoscopyevery 3 to 5 years after age 50.
4. The colon can be inspected by

• DRE, to inspect the distal 8 cm of colon.
• flexible sigmoidoscopy, to examine the distal 60 cm of colon.
• proctosigmoidoscopy with a rigid proctoscope, to inspect the distal 20 cm to 25 cm of colon; this test can be performed in the office.
• colonoscopy, to visualize the entire colon and distal ileum.This test requires a full colonic preparation and sedation for discomfort. Biopsy, polypectomy, and therapeutic measures for hemostasis can be performed.

3. Staging of colon cancer (Tables 14-1 and 14-2)
4. The TNM (tumor-node-metastasis) classificationis currently the preferred staging system.

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1. The Astler-Coller modification of Dukes staging systemis based on the pathology of the resected specimen.

Table 14-1. TNM Classification System for Staging of Colon Cancer

Primary tumor (T) TX Tumor cannot be assessed T0 No primary tumor found Tis Carcinoma in situ T1 Invasion into the submucosa T2 Invasion into the muscularis propria T3 Invasion through the muscularis and into the serosa or pericolic tissues T4 Invasion into adjacent structures or organs Regional lymph nodes (N) NX Regional nodes cannot be assessed N0 No regional node involvement N1 Metastasis in 1 to 3 pericolic nodes N2 Metastasis in 4 or more pericolic nodes N3 Metastasis in any nodes along the course of named vascular trunks Distant metastasis (M) MX Presence of distant metastasis cannot be assessed M0 No distant metastasis M1 Distant metastasis TNM = tumor, node, metastasis.

Table 14-2. Comparison of Staging Systems for Colon Cancer

Description of Cancer Astler-Coller Modification of Dukes Staging TNM Classification AJCC/UICC 5-Year Survival Rate Cancer limited to the mucosa but not through the muscularis propria and negative lymph nodes A Tis/N0/M0 T1 or T2/N0/M0 Stage 0 Stage I 90% Limited to the muscularis propria, with negative nodes B1 T3/N0/M0 Stage II 70%–75% Full thickness invasion, with negative nodes B2 T4/N0/M0 Stage B1 invasion with positive nodes C1 Any T/N1, N2, or N3/M0 Stage III 35% Stage B2 invasion with positive nodes C2 Distant metastasis regardless of invasion D Any T/any N/M1 Stage IV < 5% AJCC = American Joint Committee on Cancer; UICC = International Union Against Cancer (Union International contre le cancre).

4. Treatment of colon cancer
5. Surgical interventionconsists of two different resection approaches:

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1. Resection with primary anastomosis, if a bowel preparation can be performed before surgery (single-stage procedure)
2. Resection with creation of a colostomy, if a bowel preparation cannot be performed (two-stage procedure)

. Reanastomosis of bowel after a colostomy is generally performed at or after 6 weeks.

1. This technique is generally used for obstructing lesions.
2. Segmental resectionfor colonic lesions depends on the segmental distribution of the arterial supply to the affected area.
3. The mesenteric blood supply to the diseased segment is divided with resection of all accompanying mesenteric lymph nodes.
4. Appropriate segmental resections for colonic tumors include

• right hemicolectomyfor cecal and ascending colon tumors.
• transverse colectomyfor tumors in the transverse colon.
• left hemicolectomyfor tumors in the splenic flexure and descending colon.
• sigmoid colectomyfor tumors in the sigmoid colon.

1. Current chemotherapeutic agents

• include 5-fluorouracil and levamisole used alone, or with other drugs.

1. Types of chemotherapy

. Adjuvant therapy

• is administered after complete tumor resection to eliminate any microscopic metastatic disease.

1. Neoadjuvant therapy

• is administered before other treatments to induce tumor shrinkage and eliminate occult metastatic disease.

1. Palliative therapy

• is administered to patients with locally advanced disease not amenable to surgery.

2. Indications for chemotherapy

• Chemotherapy improves survival in Stage III colon cancer and is recommended as adjuvant therapy in these patients.
• There is no efficacy for chemotherapy in Stage I or II cancers.

1. Radiation therapy

• is generally not used in treating colonic adenocarcinoma.

1. Postoperative surveillance
2. Physical examination, laboratory tests (e.g., complete blood count, liver function tests), and tests for tumor markers [e.g., carcinoembryonic antigen (CEA)] are recommended every 3 months for the first 2 years, then less frequently thereafter.
3. Chest radiographshould be performed annually for 5 years.
4. Barium enema or colonoscopyis recommended every 3 years.

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1. Special considerations for adenocarcinoma of the rectum
2. Tumors confined to the pelvis usually make wide excision impossible.
3. The proximity of the sphincter mechanism poses potential problems with incontinence.
4. A permanent colostomymay be necessary if the lesion is too close to the sphincter.
5. The proximity to the organs and nerve supply of the urogenital tract may also lead to a high rate of impotencein men.
6. There is a greater risk of local and regional tumor recurrencein the rectum versus the colon.
7. Preoperative evaluation for suspected rectal cancer
8. Local evaluation of the primary tumor

• DREcan estimate size and fixation.
• Rigid sigmoidoscopyallows for adequate biopsy and reliable estimation of the distance of the tumor from the anal verge.
• Transanal ultrasoundmay be used to determine depth of invasion.

1. Regional evaluation to determine resectability and local invasion

• The urogenital tract can be evaluated with ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), or cystoscopy, as well as a pelvic examination in women

3. Treatment of rectal cancer
4. Surgical optionsfor the resection of rectal tumors (Figure 14-3)
5. Transanal local excision may be performed for small distal tumors confined to the mucosa.
6. Low anterior resectionis used for mid and upper rectal lesions.

• The distal colon and proximal rectum are resected with primary anastomosis performed above the levator ani muscle.
• The sphincter mechanism is preserved.

3. Abdominoperineal resectionis used for lower rectal lesions.

• The anal canal below the level of the sphincter is excised along with the rectum with formation of a sigmoid colostomy.

1. Radiation therapy

• has a role, unlike in colon adenocarcinoma.

1. Preoperativeradiation can be used to reduce tumor mass and potentially make an unresectable tumor resectable.
2. Radiation therapy can also allow for a less radical resection that will preserve the anal sphincter.
3. Postoperativeradiation can be used to decrease the rate of local recurrence.
4. Chemotherapy regimens

• are similar to those used for adenocarcinoma of the colon (see III A 4 c).

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Figure 14-3. Resections for low colonic and rectal cancer. The low anterior resection is used for cancers in the upper rectum or distal colon and consists of a distal resection with reanastomosis either immediately or at a later date after formation of a temporary colostomy (Hartmann's operation). The latter is generally used in emergent cases when the bowel is not prepared adequately. An abdominal perianal resection is used when the cancer is too distal to allow for future anastomosis. (Reprinted with permission from Schwartz S: Principles of Surgery, 7th ed. New York, McGraw-Hill, 1998, p 1357.)

1. Neoplasms of the Anus
2. Squamous cell carcinoma

• of the anus generally presents with pruritus, bleeding, and a palpable mass.

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1. Early lesions can be treated with wide local excision.
2. More advanced lesions that involve the sphincters can be treated with combined chemoradiationtherapy.
3. Resection with abdominoperineal resection(APR) is reserved for persistent or recurrent disease.
4. Other rare neoplasms of the anus

• may mimic squamous cell carcinoma.

1. Basal cell carcinomais treated with wide local excision.
2. Bowen's disease, or squamous cell carcinoma in situ, is also adequately treated with wide local excision.
3. Symptomatic malignant melanomaof the anus is usually associated with significant metastatic disease at the time of diagnosis.
4. Perianal Paget's diseaseis frequently associated with an underlying large bowel malignancy.
5. Verrucous carcinoma, also called giant condyloma or Buschke-Löwenstein tumor, is a large, wart-like lesion that is soft and slow growing.
6. Inflammatory Diseases of the Colon
7. Infections can cause or mimic surgical problems.
8. Pseudomembranous colitis

• secondary to Clostridium difficileinfection can arise after antibiotic administration (see Chapter 4 III D 1).

2. Mesenteric adenitis

• secondary to viral infection or Yersinia enterocoliticainfection can mimic appendicitis.

3. Other inciting organisms

• may include Salmonella, Shigella, and Cytomegalovirus.

4. Neutropenic enterocolitis

• (e.g., following chemotherapy) may also mimic surgical disease.

1. Inflammatory bowel disease (Table 14-3)
2. Ulcerative colitis
3. Signs and symptoms

• include bloody diarrhea, urgency, abdominal pain, fever, and weight loss.

1. The rectum is always involvedand there is spread proximally in a continuous fashion without “skip areas.”

• With proximal colonic involvement, the terminal ileum may be affected by a process called “backwash ileitis.”

1. Mucosal and radiographic findings

• Acute disease shows serrated mucosa.
• Chronic disease results in effacement of haustra and shortening of the colon causing a “lead pipe”appearance on barium enema.

1. The risk of developing colon cancer

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• with ulcerative colitis is 1% per year after 10 years of disease (10% at 20 years).

Table 14-3. Features of Ulcerative Colitis and Crohn's Disease

Ulcerative Colitis Crohn's Disease Distribution Affects only the colon and rectum. May affect any part of the bowel from mouth to anus Histology Crypt abscesses and psuedopolyps. Involves only the mucosa and submucosa. Noncaseating granulomas. Involves the entire bowel wall. Complications Strictures and fistulas are rare. Toxic megacolon can occur. Strictures and fistulas are common. Toxic megacolon can occur. Pattern of progression Always involves the rectum and progresses proximally in a continuous fashion. Rectum may be spared. “Skip lesions” are common. Cancer risk Increased risk for cancer (10% at 20 years); greater than in Crohn's disease. Increased risk for cancer, although not as great as in ulcerative colitis. Role of surgery Surgery can be curative. Surgery is not curative and is reserved for treatment of disease complications. Extracolonic manifestation Arthritis and ocular manifestations often parallel severity of colonic disease. Erythema nodosum and pyoderma gangrenosum are also seen. Erythema nodosum, iritis, uveitis, pyoderma gangrenosum, arthritis, spondylitis, sclerosing cholangitis, aphthous stomatitis, and pericholangitis.

1. Medical management

• is generally the primary therapyfor uncomplicated disease.

2. Maintenance with sulfasalazineis used to decrease relapse rates.
3. Topical treatment (enemas) with metronidazole or steroid therapymay be used to treat acute exacerbations.
4. Other immunosuppressive agents (e.g., azathioprine) may be used in some cases.
5. Surgical indications for ulcerative colitis
6. Emergency colectomy

• is recommended for complications such as hemorrhage and toxic megacolonthat do not respond promptly to medical management.

1. Elective colectomy

• is recommended for disease refractory to medical managementand for cancer prophylaxis in long-standing disease (> 10 years).

1. The entire colon is resected and if rectal disease is mild, the rectum may be left in place and ileorectal anastomosis performed.

• This requires close follow-up surveillance of the rectal stump for evidence of cancer.

1. If the rectum is removed, surgical options include a permanent ileostomy or creation of an ileal pouch with ileoanal anastomosis (Figure 14-4).

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1. Surgical therapy is curative if the entire colon and rectum are removed.

Figure 14-4. Surgical options in the treatment of ulcerative colitis. In the event that the entire colon is removed to provide a surgical cure for ulcerative colitis, two options are available postoperatively. (A) A permanent ileostomy may be performed following complete resection. (B) The ileal pouch with ileoanal anastomosis may provide the patient with more normal bowel function, although bowel movements may remain frequent and watery. The temporary ileostomy is used to divert the flow of small bowel content to protect the ileal anastomosis in the postoperative period. It is taken down at a later date. (Reprinted with permission from Schwartz S: Principles of Surgery, 7th ed. New York, McGraw-Hill, 1998, p 1322.)

2. Crohn's disease(see Chapter 13)

• A comparison of Crohn's disease and ulcerative colitis is summarized in Table 14-4.

1. Diverticular Disease and Volvulus
2. Diverticular disease of the colon
3. Diverticuli

• are herniations of mucosa through the colon wall at the sites where arterioles enter the muscular wall.

1. They are most prevalent in the sigmoid colon, but can occur in any portion.
2. Increased intraluminal pressure forces the mucosa to herniate.
3. Diverticulosis

• is a common cause of massive lower gastrointestinal bleeding.
• usually presents as bright-red blood from the rectum, although there are many other potential sources (see Table 14-4).

1. Hemorrhageis the most common complication of diverticulosis.

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1. The close association of the arteriole with the diverticulum can result in erosion into the vessel and massive hemorrhage.

Table 14-4. Causes of Gastrointestinal (GI) Bleeding Distal to the Ligament of Treitz (Lower GI Bleeding)

Diverticulosis (most common cause of massive bleeding from the rectum) Angiodysplasia (frequent source of right-sided colonic bleeding) Cancer (most common cause of occult blood loss) Inflammatory bowel disease (i.e., ulcerative colitis and Crohn's disease) Hemorrhoids Small bowel tumors Upper GI bleeding (may frequently present as bleeding from the rectum) Infectious colitis Benign colonic lesions (polyps) Aortoenteric fistula (should be considered with a history of aortic aneurysm repair) Ischemic colitis

3. Diverticulitis

• denotes infection and inflammation of the colonic serosa as well as the surrounding soft tissues.

1. Infection is a result of small perforations in the diverticulum with fecal contamination.
2. In most cases, spillage is minimal and infection is confined locally.
3. Symptoms include left lower quadrant (LLQ) abdominal pain, fever, chills, and alterations in bowel habit (constipation or diarrhea).

• Diverticulitis is usually not associated with bleeding.

1. A CT scanis a useful diagnostic test for suspected diverticulitis.
2. Most cases respond to medical management with antibiotics and bowel rest and do not require surgical intervention.
3. Complications of diverticular disease

• frequently require surgical intervention.

1. Uncontrolled hemorrhage

• secondary to diverticulosisshould be approached with a full lower gastrointestinal bleed work-up even with known diverticular disease (Figure 14-5).

2. Colonic bleeding will stop spontaneously in 85% of cases;however, resection of the diseased area may be necessary for refractory bleeding.
3. The sites of bleeding should be localized if possible with a nuclear bleeding scan or angiography.
4. If the bleeding site is identified, a segmental colectomy can be performed. If the site is not found, a subtotal colectomy for refractory bleeding may be required.
5. Complicated diverticulitis

• (e.g., abscess or fistula formation, perforation, obstruction) may require emergent surgical resection.

1. The most common fistulas are between the bladder and colon in men, and the colon and vagina in women.

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2. Some abscesses can be drained percutaneously and the diseased segment of colon resected electively at a later date.
3. Recurrent diverticulitis

• may require surgical intervention.

1. Uncomplicated diverticulitisis treated with bowel rest and broad-spectrum antibiotic therapy with a low recurrence rate after one episode.
2. Second attacks are associated with a 50% chance of recurrenceand elective resection is recommended after symptoms resolve.

Figure 14-5. The work-up of acute lower gastrointestinal bleeding. GI = gastrointestinal; NG = nasogastric; RBC = red blood cell.

1. Colonic volvulus

• involves twisting of the bowel and usually results in obstruction, with the sigmoid and cecum being the most common sites.

1. Sigmoid volvulus

• accounts for about 80%of colonic volvulus.
• is the most common cause of bowel obstruction in pregnancy.

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1. Sigmoid volvulus is more common in older and institutionalized patientsin whom a redundant sigmoid is often seen because of chronic constipation.
2. Patients present with abdominal pain, distention, and obstipation.
3. Plain radiographs of the abdomen reveal a dilated sigmoid that appears as a U-shaped loop in the lower abdomen.
4. Sigmoidoscopy is often both diagnostic and therapeutic.
5. Volvulus reduction and bowel decompression by sigmoidoscopy should be followed by elective sigmoid resection because there is a 40% rate of recurrence without operative intervention.
6. If the volvulus cannot be reduced or if there are signs of bowel gangrene (e.g., peritoneal irritation, elevated white blood cell count, sepsis), the patient should be taken to surgery emergently.
7. Cecal volvulus

• accounts for less than 20%of colonic volvulus.

1. Patients present with symptoms of small bowel obstruction and may have a history of intermittent symptoms.
2. Plain radiographs of the abdomen reveal the kidney bean–shaped, air-filled cecum located in the left upper quadrant (LUQ)[Figure 14-6].
3. Operative detorsion with cecopexy (suturing the cecum in place) is associated with recurrence, and right hemicolectomy is generally considered the treatment of choiceto avoid recurrence.

VII. Benign Anorectal Disease

1. An anal fissure

• is described as a split in the anoderm in either the anterior or posterior (90%) midline.

1. Recurrent fissures

• or fissures occurring laterally should raise suspicion of a contributing disease process (e.g., Crohn's disease).

2. Symptoms associated with fissures

• Patients generally complain of painful defecation or bleeding from the rectum.
• Pain in the fissurecauses internal sphincter spasm and further tearing.

3. Diagnosis and management
4. Inspectionof the perianal area may reveal the fissure.
5. DREwith adequate anesthesia may reveal a hypertrophied sphincter.
6. Stool softeners, bulk laxatives, and warm sitz baths will heal 90% of cases.
7. Surgical interventionfor persistent fissures includes stretching or division of the distal internal sphincter (sphincterotomy).
8. Anorectal abscess

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Figure 14-6. Barium enema demonstrating a sigmoid volvulus. Note loop of massively dilated colon and barium stopping at the point of obstruction. (Reprinted with permission from Daffner RH: Clinical Radiology: The Essentials, 2nd ed. Baltimore, Williams & Wilkins, 1999, p 261.)

1. Potential spaces for abscess formation

• include the perianal and intersphincteric spaces, the ischiorectal fossa, or above the levator ani muscles (supralevator) [Figure 14-7].
• The ischiorectal and supralevator spaceshave a posterior communication that may allow for “horseshoe” abscess formation.

2. Signs and symptoms

• Symptoms include severe anal pain, fever, urinary retention, and occasionally sepsis.
• A palpable mass is often noted on DRE.

3. Treatment

• Incision and drainageshould be performed as soon as possible.
• Perianal and ischiorectal abscesses can be drained through the overlying skin.
• Supralevator abscesses may be drained internally through the rectal wall.

1. Perianal fistula (fistula-in-ano)

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Figure 14-7. Perirectal spaces. (Reprinted with permission from Schwartz S: Principles of Surgery, 7th ed. New York, McGraw-Hill, 1998, p 1303.)

1. The most common causeof anal fistula formation is spontaneous drainage of an anorectal abscess, resulting in a persistently draining tract.

• Other causes include Crohn's disease, trauma, and radiation.

2. Diagnosis and treatment
3. Patients generally present with a chronically draining wound or recurrent anorectal abscesses.
4. Goodsall's rule(Figure 14-8) divides the anus into anterior and posterior halves.

• External openings in the anterior halfwill connect to an internal opening via a direct fistula tract.
• External openings in the posterior halfwill connect to a posterior midline internal opening via a curved tract.

1. Fistulas are generally treated by incising the fistula (fistulotomy) and curetting the tract. The wound then heals by secondary intention.
2. Pilonidal disease

• represents sinus or abscess formation in the skin and subcutaneous tissues over the sacrococcygeal junction.

1. These lesions are more common in menand infection may be secondary to fragmented hairs driven into the skin.
2. Acute infectionpresents with pain and swelling and incision and drainage should be performed.
3. After acute infection subsides, persistent sinus tracts should be excised.
4. Hemorrhoidal tissue

• is found at the right anterolateral and posterolateral positions and the left lateral position.

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Figure 14-8. Goodsall's rule. Fistulae with an external opening posterior to the line bisecting the anorectum have internal openings in the midline. Those anterior to the line have internal openings that connect via a straight, radial line. (Reprinted with permission from Nyhus, LM: Mastery of Surgery, 3rd ed. Philadelphia, Little, Brown, 1997, p 1566.)

1. Internal hemorrhoids

• are above the dentate line (an insensate area) and are covered by mucosa.

1. These lesions rarely cause painunless incarcerated.
2. Patients usually complain of painless bleeding or prolapse.
3. External hemorrhoids

• are distal to the dentate line and are covered by sensate squamous epithelium.

1. Common symptoms include perianal pain, itching, and swelling.
2. Acute pain and swelling is suggestive of acute thrombosis.
3. Treatment of hemorrhoids

• Initial treatmentincludes fiber diet, stool softeners, and avoidance of straining.
• Insensate internal hemorrhoidsmay be treated by rubber-band ligation resulting in necrosis and sloughing of the lesion.
• Sclerosis and cryosurgery are other techniques used to treat internal hemorrhoids.
• Excisional hemorrhoidectomyis the best choice for symptomatic hemorrhoids with a substantial external component or internal hemorrhoids refractory to banding.

1. Rectal prolapse

• is a complete intussusception of the rectum through the anus.

1. This process involves all layers of the rectumand appears as a large mass protruding from the anus.
2. Folds in the mucosa are circumferential as opposed to radial, which differentiates

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rectal prolapse from other conditions such as prolapsed hemorrhoid or rectal polyp.

3. Rectal prolapse is more common in elderly women and institutionalized patientsand is associated with long-term anal outlet obstruction.

• Patients are often incontinent of stool and have pudendal neuropathy.

4. Treatment involves rectopexy (fixation of the rectum)in the absence of a redundant sigmoid or low anterior resection of the rectosigmoid colon.

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Review Test

Directions: Each of the numbered items or incomplete statements in this section is followed by answers or by completions of the statement. Select the ONE lettered answer or completion that is BEST in each case.

1. A 44-year-old woman with a 24-year history of ulcerative colitis presents with persistent melanotic, loose stools for the past 6 months. Her disease had been well controlled medically with steroids until her recent problems. Colonoscopic biopsy of a 6-cm mass in the descending colon reveals adenocarcinoma. After the proper procedure is performed in this patient, which of the following pathologic characteristics of ulcerative colitis might be seen in the resected segment?

(A) Full thickness involvement

(B) Sparing of the rectal segment

(C) Crypt abscesses

(D) “Creeping fat” around the affected bowel

(E) Segments of normal bowel between areas of disease (“skip areas”)

1–C. Of the listed gross and microscopic pathologic findings, only crypt abscesses are characteristic of ulcerative colitis. The remaining findings are typically seen in Crohn's disease. Ulcerative colitis involves only the mucosa and submucosa and virtually always involves the rectum and spreads proximally. “Creeping fat” is not unique to Crohn's disease and can be seen in any full thickness inflammatory process involving the bowel.

Questions 2-3

An 83-year-old woman in a nursing home presents with a 24-hour history of obstipation and distended abdomen. Her vital signs and laboratory tests are normal. Plain abdominal film reveals a massively dilated loop of bowel in the lower abdomen.

2. Which of the following is the most likely diagnosis for this patient?

(A) Small bowel obstruction

(B) Fecal impaction

(C) Cecal volvulus

(D) Sigmoid volvulus

(E) Ogilvie's syndrome

2–D. Sigmoid volvulus is most common in elderly and institutionalized individuals and usually presents with acute obstruction, abdominal distention, and obstipation. Plain films reveal a U-shaped, dilated loop of bowel in the lower abdomen. Ogilvie's syndrome, or colonic pseudo-obstruction, usually involves the entire large bowel. Small bowel obstruction would appear as “stair stepping” of loops of small bowel on plain film examination. Cecal volvulus appears as a bean-shaped loop of bowel in the left upper quadrant (LUQ) of the abdomen.

3. Which of the following is the most appropriate next step in the treatment of this patient?

(A) Immediate surgery

(B) Flexible sigmoidoscopy

(C) Barium enema

(D) Admission and observation

(E) Discharge with laxatives

3–B. Sigmoidoscopy is usually both diagnostic and therapeutic in cases of sigmoid volvulus. Decompression should be followed by elective sigmoid resection to prevent recurrence of the volvulus. A barium enema study would be helpful in confirming the diagnosis but would not be therapeutic and is not the best choice in treating this patient. Immediate surgery is not indicated because the volvulus may be reduced by colonoscopy, allowing for an adequate bowel preparation and elective sigmoid resection with a primary anastomosis. Should colonoscopic reduction of the volvulus not be possible, emergent surgical resection with formation of a colostomy would be indicated.

Questions 4-5

A 35-year-old truck driver presents with perianal pain and pain on defecation for 2 days. He has no prior history of medical problems and reports only a low-grade fever. Digital rectal examination (DRE) reveals a tender mass at the anal verge.

4. Which of the following is the most likely diagnosis for this patient?

(A) Perianal abscess

(B) Supralevator abscess

(C) Hemorrhoids

(D) Anal fissure

(E) Rectal cancer

4–A. Perianal abscess is the most likely etiology of acute-onset perianal pain with fever. A supralevator abscess would be higher in the rectum and would not likely be palpable on digital rectal examination (DRE). Hemorrhoids are not generally tender unless thrombosed nor do they present with fever. An anal fissure would not likely be associated with fever or a tender mass. Rectal cancer would be unlikely in this patient and generally presents as an ulcerated mass that is usually not painful.

5. Which of the following is the most appropriate next step in the management of this patient?

(A) Admission and antibiotics

(B) Incision and drainage

(C) Excisional hemorrhoidectomy

(D) Lateral sphincterotomy

(E) Colonoscopy

5–B. Incision and drainage without delay is the most appropriate treatment for a perirectal or perianal abscess. Attempts to treat with antibiotics in the absence of drainage are generally unsuccessful. Colonoscopy is generally not indicated unless there is concern of some underlying colonic pathology such as ulcerative colitis or Crohn's disease. Lateral sphincterotomy is the treatment for anal fissures that are refractory to conservative therapy.

Questions 6-7

A 67-year-old man presents with sudden onset massive bleeding from the rectum. He has no prior history of gastrointestinal problems and denies any abdominal pain. He has been previously healthy and takes no medications. A nasogastric tube is placed and clear bile without blood is aspirated from the stomach.

6. All of the following would be an appropriate next step EXCEPT:

(A) Bleeding scan

(B) Type and crossmatch

(C) Colonoscopy

(D) Angiography

(E) Admission to the hospital

6–C. The patient should be admitted, typed and crossmatched for blood, and observed for further bleeding. Bleeding scan and angiography can locate the area in question if the patient is actively bleeding (at least 0.5 mL/min for bleeding scan and 1.0 mL/min for angiography). However, colonoscopy is usually not useful because the large amount of bleeding in the colon usually makes visualization of the colonic mucosa impossible. Colonoscopy would be an appropriate diagnostic step if the bleeding stopped and if the colon could be adequately prepped.

7. Which of the following is the most likely cause of the massive lower gastrointestinal bleeding in this patient?

(A) Hemorrhoids

(B) Cancer

(C) Peptic ulcer disease

(D) Diverticulosis

(E) Ischemic colitis

7–D. The most common causes of massive lower gastrointestinal bleeding in adults are diverticular disease and angiodysplasia. Although not a choice in this question, angiodysplasia consists of arteriovenous malformations of the mucosa that are a frequent cause of right-sided colonic bleeding. Angiodysplasia can frequently be treated by colonoscopic coagulation of the lesion. Hemorrhoids and colon cancer rarely cause massive lower gastrointestinal bleeding although colon cancer is a frequent cause of occult gastrointestinal bleeding. Ischemic colitis may cause lower gastrointestinal bleeding but is characteristically associated with severe abdominal pain.

Questions 8-9

A 27-year-old woman presents with a history of chronic bloody diarrhea, abdominal cramping, and weight loss. The diagnosis of ulcerative colitis is made.

8. Which of the following is true regarding the management of this patient?

(A) High-dose steroids are used as a maintenance therapy to prevent relapse

(B) Surgery is rarely curative in this disease

(C) An appropriate surgical option would include a total proctocolectomy

(D) Barium enema is the diagnostic test of choice for this disease

(E) The risk of cancer is 70% after 20 years of active disease

8–C. Appropriate surgical options for ulcerative colitis include total proctocolectomy with an end ileostomy or with an ileoanal anastomosis. Subtotal colectomy with ileorectal anastomosis can also be performed in patients with ulcerative colitis if rectal disease is mild. This provides a better chance for rectal continence and more normal bowel function. However, the rectum should be monitored closely because cancers can still arise in this segment. Surveillance is easily done in the office with a rigid proctoscope. Steroids are used to treat acute exacerbations of the disease and are not used for maintenance therapy. Colonoscopy is generally considered to be the most appropriate diagnostic test for identifying ulcerative colitis. The risk of developing colon cancer is 10% at 20 years.

9. Which of the following is true regarding the surgical management of this disease?

(A) Removal of the entire colon is rarely necessary

(B) If the rectum is removed it is impossible to provide anal continence for the patient

(C) Because the cancer risk is so high in this disease, subtotal colectomy is recommended as soon as the diagnosis is made

(D) This disease is confined to the colon and does not affect other parts of the bowel

(E) Surgery offers the best chance for cure in these patients

9–E. If the entire colon and rectum are removed, surgery is essentially curative. Surgery is not indicated at the time of diagnosis if there is no sign of dysplasia on biopsy and symptoms can be controlled with medical therapy. Close follow-up is necessary to detect cancers or areas of dysplasia early. Either of these noted on colonoscopic biopsy is an indication for surgical resection. Although ulcerative colitis does not affect other parts of the bowel primarily, the distal ileum can become inflamed if the proximal colon is involved, a condition termed “backwash ileitis.”

10. A 68-year-old woman was referred by her primary care physician who noted occult positive stools on routine physical examination. Barium enema subsequently revealed a mass in the ascending colon. The appropriate examination was performed and the lesion was found to be a poorly differentiated adenocarcinoma. At surgery, the mass was noted to invade through the entire thickness of the bowel with two positive nodes and no distant metastases. Which of the following is the stage of this cancer according to the Astler-Coller modification of Dukes staging system?

(A) D

(B) B1

(C) B2

(D) C1

(E) C2

10–-E. Nodal disease automatically makes this lesion a Dukes stage C in the Astler-Coller modification system. Full thickness invasion places it in the C2 category, worsening the prognosis.

Directions: Each set of matching questions in this section consists of a list of four to twenty-six lettered options followed by several numbered items. For each numbered item, select the appropriate lettered option(s). Each lettered option may be selected once, more than once, or not at all.

Questions 11-20

1. Ulcerative colitis
2. Crohn's disease
3. Salmonellaenterocolitis
4. Yersiniaenterocolitis
5. Cytomegalovirus enterocolitis
6. Neutropenic enterocolitis
7. Pseudomembranous colitis
8. Internal hemorrhoids
9. External hemorrhoids
10. Tubular adenoma
11. Villous adenoma
12. Hyperplastic polyp
13. Rectal adenocarcinoma
14. Colonic adenocarcinoma

For each patient description, select the most appropriate diagnosis.

11. A 45-year-old man presents with persistent diarrhea 3 weeks after hospitalization for sepsis. (SELECT 1 DIAGNOSIS)

11–G. This patient likely received multiple antibiotics during his recent admission for sepsis. Thus, antibiotic-associated pseudomembranous colitis caused by Clostridium difficile is the most likely cause of those listed. It is important to remember that pseudomembranous colitis can follow the administration of any antibiotic and the onset of symptoms can be as many as 6 weeks after discontinuing antibiotic therapy.

12. A 32-year-old woman presents with 4 months of chronic diarrhea, which is occasionally bloody. Rigid proctoscopy is normal. (SELECT 1 DIAGNOSIS)

12–B. Although both Crohn's and ulcerative colitis can present in this manner, Crohn's would be a more likely diagnosis in the absence of rectal involvement. Further work-up of this patient should include colonoscopic survey of the entire colon to look for pathology and obtain biopsy as needed.

13. A 52-year-old renal transplant patient presents with bloody diarrhea and elevated liver enzymes. Colonoscopy reveals mucosal ulcerations and submucosal hemorrhage. (SELECT 1 DIAGNOSIS)

13–E. Cytomegalovirus enterocolitis generally affects immunocompromised patients such as those with acquired immune deficiency syndrome (AIDS) and transplant patients. Cytomegalovirus can also involve other organs, and the elevated liver enzymes in this patient may indicate hepatic involvement. Cytomegalovirus enterocolitis can mimic surgical problems and should be considered in any immunocompromised patient. Treatment is with gancyclovir.

14. A 45-year-old leukemic patient who is currently undergoing chemotherapy presents with abdominal pain. Abdominal films reveal air in the wall of the cecum. (SELECT 1 DIAGNOSIS)

14–F. Neutropenic enterocolitis generally affects patients receiving high-dose chemotherapy. Plain films usually reveal the appearance of obstruction with air in the wall of the bowel (pneumatosis intestinalis). These patients can be managed conservatively unless perforation of the bowel occurs. Such a complication would require emergent laparotomy and resection of the diseased segment.

15. A 16-year-old man presents with right lower quadrant (RLQ) abdominal pain and fever. The appendix is normal at operation. (SELECT 1 DIAGNOSIS)

15–D. Yersinia enterocolitica infection can cause mesenteric adenitis, which will produce symptoms identical to acute appendicitis in the absence of a diseased appendix.

16. A 67-year-old woman has a small polyp removed by colonoscopy. Pathology reveals thickened mucosa without atypia. (SELECT 1 DIAGNOSIS)

16–L. A colonic polyp that exhibits thickened mucosa without atypia on pathologic examination is a benign hyperplastic polyp and requires no further follow up.

17. A 69-year-old man presents with decreased caliber of stools and blood from the rectum. A firm mass is noted on rectal examination. (SELECT 1 DIAGNOSIS)

17–M. A firm mass in the rectum that is large enough to cause a decreased caliber of stools but is otherwise asymptomatic is likely to be a rectal cancer in a 69-year-old man. Although benign adenomas can become large enough to cause such symptoms, they generally have a rubbery consistency and do not tend to be firm on examination. Treatment would likely consist of abdominoperineal resection with subsequent chemotherapy and radiation therapy depending on the stage of the disease.

18. A 58-year-old man with a history of occult positive stools has a 3-cm polyp removed. Pathology reveals a long, finger-like glandular arrangement. (SELECT 1 DIAGNOSIS)

18–K. Villous adenomas have a long, finger-like glandular arrangement on pathologic examination. They also tend to be larger than tubular adenomas, with 60% being larger than 2 cm. Villous adenomas have a higher incidence of harboring foci of cancer and should be excised either through a colonoscope or by laparotomy and segmental resection of the involved bowel.

19. A 43-year-old woman presents with blood from the rectum after bowel movements. Rectal examination reveals a soft, spongy mass just above the dentate line. (SELECT 1 DIAGNOSIS)

19–H. Internal hemorrhoids are located just above the dentate line, are covered by mucosa, and have a soft, spongy consistency. They can prolapse and bleed but do not generally cause pain or itching. Red blood from the rectum only after bowel movement is a common complaint with internal hemorrhoid disease. Treatment consists of either rubber-band ligation or surgical excision.

20. A 31-year-old woman presents with 6 months of chronic diarrhea. Colonoscopy reveals areas of cobblestoning of the colonic mucosa dispersed between areas of normal mucosa. (SELECT 1 DIAGNOSIS)

20–B. Cobblestoning of the mucosa and “skip lesions” are typical of Crohn's disease and can be seen on colonoscopy. Ulcerative colitis tends to involve the colon in a continuous manner, starting with the rectum and moving proximally.