Diverticulosis refers to a condition in which the inner lining of the large intestine bulges out through the outer, muscular layer. These outpouchings are called diverticula. Diverticulitis refers to the development of inflammation and infection in one or more diverticula.

The chance of developing diverticula increases with age, so that by the age of 50, about 20-50% of people will have some diverticula. By the age of 90, virtually everyone will have some. Most diverticula measure about 3 mm to just over 3 cm in diameter. Larger diverticula, termed giant diverticula, are quite infrequent, but may measure as large as 15 cm in diameter.

Diverticula are believed caused by overly forceful contractions of the intestine's muscular wall. They are most common in the developed countries of the West (North America, Great Britain, northern and western Europe). This is thought to be due to the diet of these countries, which...