Colonic diverticulosis increases with age, ranging from 5% in those under age 40, to 30% at age 60, to more than 50% over age 80 years in Western societies. Most are asymptomatic, discovered incidentally at endoscopy or on barium enema. Complications occur in less than 5%, including gastrointestinal bleeding and diverticulitis.
Colonic diverticula (eFigure 15–78) may vary in size from a few millimeters to several centimeters and in number from one to several dozen. Almost all patients with diverticulosis have involvement in the sigmoid and descending colon; however, only 15% have proximal colonic disease (eFigure 15–79).
Diverticulosis. In the sigmoid colon several diverticula are visible. Diverticula are herniations of the colonic mucosa and submucosa through the muscularis. Diverticula often are seen in rows, as in this case, that correspond to sites of penetration of the bowel wall by branches of the vasa recta. (Used, with permission, from Michelle Nazareth, MD.)
For over 40 years, it has been believed that diverticulosis arises after many years of a diet deficient in fiber (eFigure 15–80). It is hypothesized that undistended, contracted segments of colon have higher intraluminal pressures. Over time, the contracted colonic musculature, working against greater pressures to move small, hard stools, develops hypertrophy, thickening, rigidity, and fibrosis. Diverticula may develop more commonly in the sigmoid because intraluminal pressures are highest in this region. Recent epidemiologic studies challenge this theory, finding no association between the prevalence of asymptomatic diverticulosis and low dietary fiber intake or constipation. Thus, the etiology of diverticulosis is uncertain. The extent to which abnormal motility and hereditary factors contribute to diverticular disease is unknown. Patients with abnormal connective tissue are also disposed to development of diverticulosis, including Ehlers-Danlos syndrome, Marfan syndrome, and scleroderma.
Top: Pathophysiology of diverticular disease. Bottom: Cross-sectional drawing of the colon, showing principal points of diverticula formation between mesenteric and antimesenteric teniae. (Reproduced, with permission, from Goligher JC. Surgery of the Anus, Rectum and Colon, 4th ed. Baillière Tyndall, 1980. Copyright © Elsevier.)
1. UNCOMPLICATED DIVERTICULOSIS
More than 90% of patients with diverticulosis have uncomplicated disease and no specific symptoms. In most, diverticulosis is an incidental finding detected during colonoscopic examination or barium enema examination. Some patients have nonspecific complaints of chronic constipation, abdominal pain, or fluctuating bowel habits. It is unclear whether these symptoms are due to alterations in the colonic motility, visceral hypersensitivity, gut microbiota, or low-grade inflammation. Physical examination is usually normal but may reveal mild left lower quadrant tenderness with a thickened, palpable sigmoid and descending colon. Screening laboratory studies should be normal in uncomplicated diverticulosis.
There is no reason to perform imaging studies for the purpose of diagnosing asymptomatic, uncomplicated disease. Diverticula are ...