Diverticulosis is the presence of multiple balloon-like sacs (diverticula), usually in the large intestine.
Diverticula may develop anywhere in the large intestine, but they are more common in the sigmoid colon, which is the last part of the large intestine just before the rectum. Diverticula vary in diameter from 1/10 inch to 1 inch (about ¼ to 2½ centimeters). They are uncommon before age 40 but become more common rapidly thereafter. Just about everyone who reaches age 90 has many diverticula. Giant diverticula, which are rare, range from 1 to 6 inches (about 2½ to 15 centimeters) in diameter. A person may have only a single giant diverticulum.
Diverticula are thought to be caused by spasms of the muscular layer of the intestine. The cause of these intestinal spasms is unknown but may be related to a low-fiber diet. The resulting pressure that these spasms exert on the intestinal wall causes a part of the wall to bulge at a point of weakness, usually near to where an artery penetrates the muscular layer of the large intestine. An increase in the thickness of the muscular layer is a common finding in the sigmoid colon of people with diverticulosis. The cause of a giant diverticulum is unclear.
Diverticula themselves are not dangerous. In fact, most people with diverticulosis do not have symptoms. However, diverticulosis can sometimes cause unexplained painful cramps, bowel movement disturbances, and blood in the stool. The narrow opening of a diverticulum can bleed, sometimes heavily, into the intestine and out through the rectum. Bleeding may also result when stool gets wedged in the diverticulum and damages a blood vessel (usually the artery beside the diverticulum). Stool that is trapped in a diverticulum may cause not only bleeding but also inflammation and infection, resulting in diverticulitis.
Diverticulosis is suspected when symptoms such as unexplained painful cramps, bowel movement disturbances, or rectal bleeding are present. The diagnosis is usually confirmed by colonoscopy or sometimes a barium enema x-ray study (see Diagnosis of Digestive Disorders: X-ray Studies). However, if the person has severe abdominal pain, computed tomography (CT) is performed instead, so as not to rupture the inflamed intestine.
If blood is present in the stool, a colonoscopy is usually the best method with which to identify the source. However, angiography or radionuclide scans taken after an intravenous injection of radioactive red blood cells may be required to determine the source of bleeding.
The goal of treatment is usually to reduce intestinal spasms, which is best achieved by maintaining a high-fiber diet (which consists of vegetables, fruits, and whole grains) and drinking plenty of fluids. An increased bulk in the large intestine reduces spasms, which in turn decreases the pressure on the walls of the large intestine. If a high-fiber diet alone is not effective, a diet supplemented daily with bran or a bulking agent, such as psyllium or methylcellulose, may help.
Uncomplicated diverticulosis, in which a person has no evidence of inflammation, infection, or complications, does not require surgery. Most bleeding stops without treatment, but if it does not, doctors often perform a colonoscopy to clot (coagulate) the bleeding area by injecting the area with a drug. If bleeding recurs often or if the source of the bleeding cannot be determined, surgery to remove most of the large intestine may be needed, but such surgery is not commonly done.
A giant diverticulum usually requires surgery, because it is likely to become infected and to rupture.
Last full review/revision November 2007 by Michael C. DiMarino, MD