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Ms. Wick is a senior clinical research pharmacist at the National Cancer Institute, National Institutes of Health, Bethesda, Maryland. The views expressed are those of the author and not those of any government agency.
Almost unheard of in developing nations, colonic diverticular disease is common in Western and industrialized societies. A relatively new disease, it is rarely mentioned in documents predating World War I. The condition surfaced when processed foods were introduced into the American diet.
Diverticulosis describes the presence of uninflamed mucosal herniations or sacs (diverticula) in the colon wall. These small pouches bulge outward through weak spots—similar to an inner tube poking through weak places in a tire. Diverticulosis is largely symptomless; however, up to three quarters of patients may have sensitive or unpredictable bowel habits.
Diverticulitis indicates inflamed diverticula, often accompanied by gross or microscopic perforations. Up to one quarter of people with diverticulum develop diverticulitis.1-4 Diverticulitis affects the sigmoid and descending colon (located on patient's left side) in >90% of patients5 and also is a relatively common cause of acute lower gastrointestinal bleeding. Patients may report blood in their stool.6
Patients are being diagnosed with diverticulitis with greater frequency, partly because age and obesity are contributing factors. Approximately 130,000 Americans, generally older than age 50 (a population that is growing in number), with equal gender distribution, are hospitalized with diverticular disease annually.1-4 It has been identified as one of the 5 most costly gastrointestinal diseases.7 Long regarded as a disease of the elderly, the incidence of diverticulitis has been increasing in those under age 40, especially in men and the obese.8
The musculature of the colon thickens with age, reflecting increasing pressures required to eliminate feces. Patients with diverticulosis often present with increased intracolonic pressure as the left colon narrows due to diverticulum formation.9,10 Diverticulosis has been associated with diets low in dietary fiber but high in refined carbohydrates, which create smaller, harder stools and may slow gastrointestinal transit time; its exact cause is still unknown.11,12 Slow transit time can increase intracolonic pressure and make bowel evacuation difficult.2 Constipation, obesity, physical inactivity, smoking, and treatment with nonsteroidal anti-inflammatory drugs also have been associated with diverticular disease.7
Should colonic diverticula become obstructed with fecal matter, several adverse outcomes may follow: sac distention, bacterial overgrowth, vascular compromise, local-tissue ischemia, and perforation. Although perforations can be localized and contained, some may invade the skin or erode adjacent viscera, causing fistulas especially among the colon, small intestine, skin, and bladder.
The chain of events is similar to that in appendicitis, and diverticulitis is often mistaken for appendicitis. Anaerobes are isolated most often, but gramnegative aerobes, especially Escherichia coli, and facultative gram-positive bacteria, like streptococci, also are found.13 Complicated diverticulitis describes an abscess or spreading, diffuse inflammatory reaction, fistula formation, stricture disease, bowel obstruction, or peritonitis.
In classic cases, patients who develop diverticulitis report severe constipation and abdominal pain in the left lower quadrant and present with leukocytosis and low-grade fever. Abdominal or perirectal fullness may be palpable, and patients may complain of bloating. Patients with perforation have marked abdominal tenderness that begins suddenly and spreads rapidly to involve the entire abdomen, causing perotinitis.2,14
Several populations tend to present atypically. Asians, including Asian Americans, have a predominance of rightsided diverticula. In immunocompromised patients, diverticulitis is generally more severe and may present with atypical signs and symptoms. These patients are more likely to have perforations, are less likely to respond to conservative management, and have higher postoperative risks than immunocompetent patients.2,14 Younger patients also are likely to present with atypical symptoms.6
Hinchey's criteria are used to classify diverticulitis into 4 stages (Table). More severe forms of diverticulitis are often accompanied by anorexia, and risk of death increases from 13% in stage 3 to 43% in stage 4.15 When acute diverticulitis is suspected, clinicians avoid using colonoscopy and sigmoidoscopy, which increase the perforation risk that can exacerbate disease. Computed tomography accurately identifies most cases of diverticulitis.16,17
Diverticulosis and diverticulitis are treated differently in different health care settings, and the conditions are chronic in nature. Understanding how exacerbations are handled in each setting can help pharmacists ensure continuity of care.