Diverticular Disease

Diseases associated with diverticula (acquired sac-like mucosal projections through the muscular layer of the GI tract), which cause symptoms by trapping feces, becoming infected, bleeding, or rupturing.

Diverticula develop in areas where circular smooth muscle has been weakened by the penetration of blood vessels to the submucosa. Usually, diverticula are found in the sigmoid and descending colons and rarely in the rectum.

Aging may lead to structural weakening of colonic muscle and the development of diverticula. In Western countries, diverticular disease occurs in about 50% of persons >= 65 years and in about 65% of those >= 80. Diverticula have been found with increasing frequency in Western populations, probably because of increased longevity and insufficient dietary fiber. A low-fiber diet may increase colonic motor activity and intraluminal pressures.

Bleeding results from rupture of the penetrating arteriole in its course around the diverticular sac and is usually brisk and painless. The origin of most diverticular bleeding, when known, is the right colon. Although 10 to 20% of patients have persistent hemorrhage, bleeding usually stops spontaneously.

Because diverticula are asymptomatic in most persons and are common in the elderly, other possible causes of nonspecific GI symptoms should be considered before attributing the symptoms to diverticula. For example, colon cancer, inflammatory bowel disease, and ischemia may mimic diverticulitis; a patient with angiodysplasia of the colon may present with brisk, painless bleeding.

Diverticulosis

Diverticula without inflammation.

Colonic diverticulosis is asymptomatic. Dietary measures aim to prevent complications (eg, diverticulitis, bleeding). However, there is no evidence that such measures prevent complications. Fiber supplements or an increased dietary fiber intake is recommended.

Painful Diverticular Disease

Diverticulosis accompanied by painful spasm or other symptoms.

Painful diverticular disease is characterized by cramps in the left lower abdomen without infection or inflammation. Symptoms are often associated with constipation or diarrhea and tenderness over the affected areas; symptoms increase after eating and may be partially relieved by defecating or passing flatus. Excessive colonic motility is the underlying mechanism producing symptoms. Symptoms of painful diverticular disease are similar to those of irritable bowel syndrome and partial bowel obstruction caused by tumors or ischemia. In contrast with diverticulitis, painful diverticular disease is not characterized by fever, leukocytosis, or rebound tenderness. Treatment aims to reduce symptoms caused by smooth muscle spasm (see Table 107-1). Fiber supplements or an increased dietary fiber intake is recommended.

Diverticulitis

Infection arising from colonic diverticula.

The incidence of diverticulitis increases with the duration of diverticulosis. Diverticulitis develops in 15 to 25% of persons with diverticulosis who are followed for >= 10 years. Diverticulitis is caused by colonic flora (eg, aerobic and anaerobic gram-negative bacilli); the role of enterococci is unknown.

Symptoms, Signs, and Diagnosis

Inflammation begins at the apex of a diverticulum when the opening becomes obstructed with stool. Fever, leukocytosis, or rebound tenderness indicates inflammation, which often remains localized in the adjacent pericolic tissues but may progress to a peridiverticular abscess. Other complications include formation of fistula to the bladder (most common), vagina, or adjacent small intestine; fibrosis and bowel obstruction; perforation with peritonitis; and sepsis. Frank rectal bleeding is not characteristic of diverticulitis.

Distinguishing between painful diverticular disease and diverticulitis is often inaccurate. In an elderly or debilitated patient, the absence of fever, leukocytosis, or rebound tenderness does not exclude diverticulitis.

If diverticulitis, abscess, or extraintestinal complications are suspected (eg, if a palpable mass is detected), a barium enema should usually be delayed by about 1 week to allow some resolution of the inflammatory process. A single contrast study can be performed with precautions to minimize the risk of perforation and extravasation of contrast material. However, abdominal CT or ultrasound provides better definition of colonic wall thickness and extraluminal structures and has supplanted contrast studies for suspected diverticulitis. CT is the most cost-effective study, with additional potential use in the treatment of abscess.

Colonoscopy is less desirable during an acute episode and is best used to exclude tumors or other conditions when other diagnostic tests are inconclusive. When contrast studies fail to identify the bleeding source, colonoscopy is indicated. Before colonoscopy is performed, colon cleansing is necessary; once the patient is stabilized and bleeding has slowed or stopped, balanced electrolyte solutions containing polyethylene glycol are given orally or by nasogastric tube. If bleeding remains brisk or the patient is unstable, selective mesenteric angiography can be used to locate the site of bleeding and to infuse vasoactive substances to control bleeding. If bleeding is intermittent or too slow to be detected by angiography, serial abdominal scans can be used (preceded by injection of technetium-99m-labelled red blood cells).

Treatment

The most important goal is to eliminate bacterial infection (see Table 107-1). If diverticulitis is mild, the patient may be treated as an outpatient with oral antibiotics and oral intake restrictions. More acutely ill patients are hospitalized.

Surgery is recommended for patients who fail to respond to medical therapy within 72 hours, for many patients who have had two or more attacks of diverticulitis, for many immunocompromised patients, and for patients whose first attack occurred before age 40. Because of the high risk of recurrences, complications, and increased morbidity, most patients with complicated diverticular disease require surgery even if clinical recovery occurs. The preferred procedure is a one-stage operation in which the diseased segment of bowel is resected and continuity restored by a primary anastomosis. If this procedure is not feasible, a two-stage operation that requires a diverting colostomy should be used.

Before elective surgery, large abscesses often can be drained percutaneously by an interventional radiologist using CT or ultrasound. Surgery may be performed after successful drainage and 2 to 3 weeks of antibiotic therapy.

Emergency surgery is required for generalized peritonitis, persistent high-grade bowel obstruction, or rapid, unremitting GI bleeding. Elderly patients with generalized peritonitis require immediate excision of the perforation site; giving antibiotics and waiting for resolution result in an extremely high mortality.