Management of Diverticular Disease

James M. Richter

Diverticula—abnormal herniations of colonic mucosa through the muscularis—are extremely common, and their prevalence increases with age. Autopsy studies estimate their presence in 20% of people older than 40 year, which increases to nearly 70% by age 70 years. About 15% of people with the condition develop attacks of diverticulitis, in which the diverticula become plugged and inflamed. It is possible that the recent emphasis on increasing the fiber content of the diet will reduce the incidences of diverticula and their complications in Western countries. The primary physician encounters many elderly patients with gastrointestinal (GI) complaints referable to diverticular disease. The physician must effectively and economically recognize and treat mild manifestations of disease, reduce the chances of complications, and decide when admission and surgical intervention are necessary.

PATHOPHYSIOLOGY, CLINICAL PRESENTATION, AND COURSE (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and 13)

Pathophysiology

Increased intracolonic pressure causes herniation of colonic mucosa. Consequently, diverticula occur most frequently in the sigmoid colon, where the colon is narrowest and pressure is greatest; however, diverticula can occur anywhere within the colon, including the ascending portion, which makes for atypical clinical presentations. In Western populations, about 85% of diverticula are found in the distal colon, with 15% located in the right side of the large bowel; in Asia, right-sided involvement is more common. Diverticula show a predilection for points of relative weakness in the muscularis, especially where branches of the marginal artery penetrate the colonic wall. The possibility of muscular degeneration has been suggested but is unproven. Research indicates that the low fiber content of modern diets has an important causal role, resulting in the production of less-bulky stool and increased intracolonic pressure. Irritable bowel syndrome, with its abnormal colonic motor activity and segmentation, might contribute to diverticular formation by way of increased intraluminal pressures.

The diverticular sac that ensues is a thin, purely mucosal structure. Obstruction of the sac’s neck by undigested food residues or a fecalith leads to distention and microabscess formation as mucous secretions accumulate and bacteria proliferate. If the blood supply to the sac becomes mechanically compromised, the sac may perforate. Microperforations commonly occur, producing peridiverticular and pericolonic inflammation and abscess formation. Walling off is the rule because these perforations typically occur adjacent to the mesocolon. The bowel lumen is typically uninvolved. Even if a peridiverticular abscess ruptures into the peritoneal cavity, gross peritonitis from fecal soilage usually does not occur because the diverticular neck is sealed by obstructing material. The bacteriology of the abscesses is predominated by anaerobes, Escherichia coli, and streptococci.

A less-common but potentially catastrophic complication of diverticulosis is free colonic perforation, which occurs from the rupture of an uninflamed diverticulum. Fecal soilage follows because there is no plug in the diverticular neck to prevent leakage of bowel contents. Frank peritonitis is the consequence.

Clinical Presentation and Course

Diverticulosis

Diverticulosis is usually asymptomatic and often discovered incidentally on screening colonoscopy, abdominal computed tomography (CT), or barium enema. However, colonic motor activity is sometimes disturbed, and intermittent left lower quadrant pain may result. Constipation is common, as is constipation alternating with diarrhea, and occasionally, there is tenderness.

Complications from diverticulosis include hemorrhage, microperforation (diverticulitis), perforation, and obstruction. The estimated complication rate is about 1%/year. Bleeding is a particularly important concern. Diverticular disease is one of the most common causes of lower GI bleeding (see Chapter 63); erosion into a blood vessel may result in brisk rectal hemorrhage. Perforation in the absence of diverticulitis is rare, but it is potentially catastrophic due to the high risk of fecal soilage. Diverticulitis is the consequence of microperforation and may lead to obstruction.

Diverticulitis

Diverticulitis is characterized clinically by left lower quadrant pain, tenderness, fever, and leukocytosis in a patient with known diverticulosis. Frequently, a tender mass is noted. Right-sided
presentations are possible, especially in Asian populations, and may mimic appendicitis or Crohn disease. In rare instances, there are extraintestinal manifestations (arthritis, pyoderma gangrenosum) that may simulate those of Crohn disease and lead to misdiagnosis. Bladder symptoms (dysuria, urgency, frequency) may occur if the process occurs adjacent to the bladder or bladder nerves.

Complicated diverticulitis refers to the development of abscess, fistula, stricture, bowel obstruction, or peritonitis. Frank perforations may lead to abscess formation. The abscesses may spontaneously drain into the bowel or erode into an adjacent organ, such as the ureter, bladder, or vagina, forming fistulas. Perforations that fail to become walled off may cause peritonitis. Those that enter the vagina result in vaginal gas or feces; those that erode into the urinary tract lead to dysuria or pneumaturia. Chronic inflammation can thicken the bowel wall and cause obstruction.

Clinical presentation and course can be defined in terms of stages (Hinchey classification) as follows:

Stage 1: abscess less than 4 cm, confined to the pericolic area or mesentery

Stage 2: abscess greater than 4 cm, confined to the pelvis

Stage 3: rupture of peridiverticular abscess with peritonitis

Stage 4: rupture of uninflamed bowel into free peritoneal space

The risk of death is 5% for stages 1 and 2, 13% for stage 3, and 43% for stage 4. Persons with stage 1 disease can often be managed on an outpatient basis (see later discussion). Recurrences are not uncommon, but mild recurrences do not increase the risk of complicated disease.

DIAGNOSIS (6,8,10,11,14, 15 and 16)

Diverticulosis

As noted earlier, diverticulosis is usually an incidental finding in a patient undergoing a colonoscopy, sigmoidoscopy, or barium enema for another reason. However, the diagnosis should also be considered in a patient presenting with relatively painless but brisk rectal bleeding. If the bleeding is not too severe, proctosigmoidoscopy can be performed to confirm the diagnosis and site of blood loss. A high rate of diagnostic errors has been found when barium enema is obtained in symptomatic persons, leading some to recommend that colonoscopy follow the barium enema. There is no contraindication to colonoscopy in asymptomatic persons with suspected diverticulosis; in the absence of inflammation, risk of perforation is small.

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