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Diverticulitis
(Diverticulosis)

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Medical Author:

Jay W. Marks, MD

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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What is diverticulitis?

Diverticulitis is a condition in which diverticuli in the colon rupture. The rupture results in infection in the tissues that surround the colon.

What is diverticulosis?

The colon (large intestine) is a long tube-like structure that stores and then eliminates waste material. Pressure within the colon causes bulging pockets of tissue (sacs) that push out from the colonic walls as a person ages. A small bulging sac pushing outward from the colon wall is called a diverticulum. More than one bulging sac is referred to in the plural as diverticula. Diverticula can occur throughout the colon but are most common near the end of the left colon referred to as the sigmoid colon. The condition of having these diverticula in the colon is called diverticulosis.

A person with diverticulosis may have few or no symptoms. When a diverticulum ruptures and infection sets in around the diverticulum, the condition is called diverticulitis. An individual suffering from diverticulitis may have abdominal pain, abdominal tenderness, and fever. When bleeding originates from a diverticulum, it is called diverticular bleeding. A person who suffers the consequences of diverticulosis in the colon is referred to as having diverticular disease.

Diverticular disease is common in the Western world but is extremely rare in areas such as Asia and Africa. Diverticular disease increases with age. It is uncommon before the age of forty, and is seen in more than fifty percent of people over the age of 60 years in the United States. Whereas most patients with diverticular disease have no or few symptoms, some patients will develop bleeding, rupture and infection (diverticulitis), constipation, diarrhea, abdominal cramps, and even colonic obstruction.

How do diverticula form?

The muscular wall of the colon grows thicker with age, although the cause of this thickening is unclear. It may reflect the increasing pressures required by the colon to eliminate feces. For example, a diet low in fiber can lead to small, hard stools which are difficult to pass and which require increased pressure to pass. The lack of fiber and small stools also may allow segments of the colon to close off from the rest of the colon when the colonic muscle in the segment contracts. The pressure in these closed-off segments may become high since the increased pressure cannot dissipate to the rest of the colon. Over time, high pressures in the colon push the inner intestinal lining outward (herniation) through weak areas in the muscular walls. These pouches or sacs that develop are called diverticula.