Definition of Diverticulitis:

Diverticulitis is swelling (inflammation) of an abnormal pouch (diverticulum) in the intestinal wall. These pouches are usually found in the large intestine (colon). The presence of the pouches themselves is called diverticulosis.

Causes, incidence, and risk factors:

Small, protruding sacs of the inner lining of the intestine (diverticulosis) can develop in any part of the intestine. They are most common in the colon, especially the sigmoid colon, the lowest part of the colon.

These sacs, called diverticula, occur more often after the age of 40. When they become inflamed, the condition is known as diverticulitis. Diverticula are thought to develop as a result of high pressure or abnormal pressure in the colon. High pressure against the colon wall causes pouches of the intestinal lining to bulge outward through small defects in the colon wall that surround blood vessels.

Diverticulosis is very common. It is found in more than half of Americans over age 60. Only a small percentage of these people will develop the complication of diverticulitis.

Diverticulitis is caused by inflammation, or (sometimes) a small tear in a diverticulum. If the tear is large, stool in the colon can spill into the abdominal cavity, causing an infection (abscess) or inflammation in the abdomen.

Risk factors for diverticulosis may include older age or a low-fiber diet.