DefinitionDiverticulitis 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 factorsSmall, 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 lini