Diverticulosis is a condition in which outpouchings form in the walls of the intestines. These pouches, known as diverticula, are about the size of a large pea. They form in weakened area of the bowels, most often in the lower part of the colon (large bowel).

Most people with diverticula do not experience any symptoms. Many may never know they have the condition, while some may feel tenderness over the affected area or have muscle spasms in the abdomen. Pain may be felt on the lower left side of the abdomen or, less often, in the middle or right side.

The diverticula themselves do not cause symptoms, but complications such as bleeding and infection may occur. Bleeding is an uncommon symptom and is usually not severe. Sometimes the pouches become infected and inflamed, this is a more serious condition known as diverticulitis. When inflammation occurs, there may be fever and an increased white blood cell count, as well as acute abdominal pain. Diverticulitis may also result in large abscesses (infected areas of pus), bowel blockage, or breaks and leaks through the bowel wall.

Often diverticulosis is discovered by an x-ray or intestinal examination done for an unrelated reason as there are likely no symptoms. The doctor may see the diverticula through a flexible tube (colonoscope) that is inserted through the anus. Through this scope, the diverticula may be seen as dark passages leading out of the normal colon wall. The doctor also may do a barium enema, an x-ray that reveals the outpouchings in the walls of the colon.

If rectal bleeding occurs, the doctor may take a special x-ray (angiography). In this procedure, dye is injected into an artery that goes to the colon, so that the site of the bleeding can be located. Diverticulitis may be diagnosed when a patient has pain and tenderness in the lower abdomen with disturbed bowel function and fever.

Diverticulosis is very common, especially in older people. Studies show that about 10% of people over the age of 40 and nearly half of people over age 60 have diverticulosis. Among those who are found to have diverticula, only about 20% develop diverticulitis, and of those, only a small number have very serious or life-threatening complications.

For most people, diverticulosis is not a problem. Diverticulitis, on the other hand, is a problem and can be a serious issue if not treated. For instance, when one of the sacs (a diverticulum) becomes infected and inflamed, bacteria enter small tears in the surface of the bowel. This leads to small abscesses. Such an infection may remain localized and go away within a few days but, in rare cases, the infection can spread and break through the wall of the colon causing peritonitis (infection of the abdominal cavity) or abscesses in the abdomen. Such infections are very serious and can lead to death unless treated quickly.

If you have diverticulosis with no symptoms, no treatment is needed. Some doctors advise eating a high-fiber diet and avoiding certain foods. Laxatives and enemas should not be used regularly. Patients with diverticulitis may be hospitalized and treated with bed rest, pain relievers, antibiotics, fluids given by vein, and careful monitoring.