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In diverticulitis, the colon or large intestine develops a diversion or outpouching that, because of its abnormal shape and position, can become irritated and cause painful symptoms. These bulges that become inflamed or infected are known as diverticula.  (A single pouch is a diverticulum.) Having diverticula is a condition called diverticulosis. The presence of diverticula or diverticulitis is referred to as diverticular disease.

Most people with diverticulosis will not develop diverticulitis. But about half of all Americans ages 60 to 80, and almost everyone over age 80, have diverticulosis at some time. The disease is common in developed or industrialized countries - particularly the United States, England, and Australia - where low-fiber diets are common. It is rare in countries such as Asia and Africa, where people eat high-fiber diets that are more heavily based on vegetable food sources.

In some cases, the diverticuli in the colon can rupture, which can result in infection in the tissues that surround the colon, a sometimes-dangerous condition. Thus serious complications of diverticulitis can include bacterial peritonitis (abdominal cavity infection), bleeding in the colon, or colon obstruction.

Causes/risk factors

Diets that are too low in fiber appear to be the main risk for diverticular disease. Fiber is the coarse part of fruits, vegetables, and grains that the body cannot digest.

The main cause of increased pressure in the colon is constipation, as a result of which muscles must strain to move stool that is hard and compacted. The excess pressure caused by straining makes the weak spots in the colon bulge out, forming diverticula. These areas are a kind of herniation of the inner intestinal lining through junctures of the muscular wall, forming a protruding pouch on the colon. Physicians do not know what causes infection in these areas, but believe it may begin when stool or bacteria are caught in the diverticula.

Signs & symptoms

Diverticulosis may not cause any discomfort for some people. For others, it may cause mild cramps, bloating, or constipation.

The most common symptom of diverticulitis is abdominal pain and the most common sign is tenderness around the left side of the lower abdomen. If diverticular bleeding occurs, blood may be present in the stool. When infection is the cause of symptoms, fever, nausea, vomiting, chills, cramping, and constipation may also occur.


In addition to taking a medical history and performing a physical examination, physicians may request the following diagnostic procedures in order to diagnose diverticulitis:

  • digital rectal examination;
  • stool sample;
  • barium, lower-GI x-ray (lower GI series or barium enema)
  • colonscopy or sigmoidoscopy;
  • ultrasound;
  • CT scan.


Treatment for diverticular disease may entail a change in diet to include more fiber. This increases stool volume and thus prevents constipation. However, once diverticula are formed, they are generally permanent unless removed surgically.

Diverticulitis can require treatment with medications for pain, infection and inflammation, and muscle spasms. Your physician may also recommend bed rest and liquid diet.

Hospitalization, blood transfusions, or surgery are sometimes required for acute attacks with severe pain, infection, or bleeding.

Surgeons on Aria's Division of Colorectal Surgery provide highly skilled and experienced surgical treatment for diverticulitis.