Incidence and Epidemiology
Among Western populations, diverticulosis of the colon affects nearly one-half of individuals older than age 60 years. Fortunately, only 20% of patients with diverticulosis develop symptomatic disease. However, in the United States, diverticular disease results in >200,000 hospitalizations annually, making it the fifth most costly gastrointestinal disorder. The incidence of the disease is on the rise, mainly among young patients. The mean age at presentation of the disease is 59 years. Although the prevalence among females and males is similar, males tend to present at a younger age. Diverticulosis is rare in underdeveloped countries, where diets include more fiber and roughage. However, shortly following migration to the United States, immigrants will develop diverticular disease at the same rate as U.S. natives.
Anatomy and Pathophysiology
Two types of diverticula occur in the intestine: true and false (or pseudodiverticula). A true diverticulum is a saclike herniation of the entire bowel wall, whereas a pseudodiverticulum involves only a protrusion of the mucosa through the muscularis propria of the colon (Fig. 297-1). The type of diverticulum affecting the colon is the pseudodiverticulum. The protrusion occurs at the point where the nutrient artery, or vasa recti, penetrates through the muscularis propria, resulting in a break in the integrity of the colonic wall. Diverticula commonly affect the sigmoid colon; only 5% of persons exhibit pancolonic diverticula. This anatomic restriction may be a result of the relative high-pressure zone within the muscular sigmoid colon. Thus, higher-amplitude contractions combined with constipated, high-fat-content stool within the sigmoid lumen results in the creation of these diverticula. Diverticulitis is inflammation of a diverticulum. The cause is not well understood and is probably multifactorial. The predominant theory is the retention of particulate material within the diverticular sac and the formation of a fecalith. Consequently, the vasa recti is either compressed or eroded, leading to either perforation or bleeding.
Gross and microscopic view of sigmoid diverticular disease. Arrows mark an inflamed diverticulum with the diverticular wall made up only of mucosa.
Presentation, Evaluation, and Management of Diverticular Bleeding
Hemorrhage from a colonic diverticulum is the most common cause of hematochezia in patients >60 years, yet only 20% of patients with diverticulosis will have gastrointestinal bleeding. Patients at increased risk for bleeding tend to be hypertensive, have atherosclerosis, and regularly use nonsteroidal anti-inflammatory agents. Most bleeds are self-limited and stop spontaneously with bowel rest. The lifetime risk of rebleeding is 25%.
Localization of diverticular bleeding should include colonoscopy, which may be both diagnostic and therapeutic in the management of mild to moderate diverticular bleeding. If the patient is stable, massive bleeding is best managed by angiography. Mesenteric angiography can localize the bleeding site and occlude the bleeding vessel successfully with a coil in 80% of cases. ...