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Diverticular Disease: Overview and Risk Factors

Diverticula are herniations, or “outpouchings,” of the colonic mucosa and submucosa through the muscularis layer. They occur at susceptible sites in the colonic wall, most commonly in areas where intramural blood vessels penetrate and weaken the muscular layer.

Diverticulosis indicates the presence of diverticula. When uncomplicated, the condition is asymptomatic. However, complications occur when diverticula become infected and inflamed (diverticulitis), which occurs in 10% to 20% of patients with diverticulosis, or when an adjacent blood vessel ruptures into a diverticulum, resulting in diverticular bleeding, which is the most common cause of lower gastrointestinal bleeding in the elderly.

Diverticulosis is usually asymptomatic, although patients may give a history of mild lower abdominal pain, cramping, bloating, constipation, and/or diarrhea. The discomfort is often relieved by bowel movements. Diverticulitis presents with fever, severe lower abdominal pain and tenderness, nausea, and vomiting. Diverticular bleeding may present as guiac–positive stools, iron–deficiency anemia, melena, or frank hematochezia.

As described below, the development of diverticula has been associated with a low–fiber diet. A lack of fiber renders the stool dry and low in bulk, requiring increased pressure to be generated by colonic contraction to propel the stool through the colon. Over time, this increased pressure is thought to result in the formation of diverticula. In contrast, high fiber intake results in stool that is of appropriate bulk and consistency, which may make the stools easier to pass.

Risk Factors

Advancing age. Diverticula are present in nearly half of Americans by age 60, and more than two–thirds of Americans over age 80 are affected. In contrast, less than 5% of people under age 40 are affected.

Geographic area. Industrialized countries have a much higher incidence of diverticular disease than developing nations. Some Western nations have prevalence rates that approach 40% of the population, whereas developing countries in Asia and Africa have prevalence well below 1%. Further, developing nations that adopt a more Western lifestyle have increased rates of diverticulosis.

Inadequate Dietary fiber intake. Several studies have linked low fiber intake to the development of diverticular disease (see Nutritional Considerations).

Total fat and red meat intake. High intake of total fat and red meat has also been correlated with a higher risk for diverticular disease.1

Sedentary lifestyle.


Diverticular Disease: Diagnosis and Treatment >>