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Diverticulosis and Diverticulitis


This information is intended only to provide general guidance. It does not provide definitive medical advice. It is important that you consult your doctor about your specific condition.


Diverticulosis is not a disease; it only describes the presence of diverticula (singular: diverticulum), which are pouches or pockets protruding from the inside of the colon out through the muscular wall of the colon (large intestine). They do not cause any problems for most people who have them. Diverticulosis is usually discovered during tests done to evaluate an unrelated medical problem or during screening, such as colonoscopy, barium enema x-ray, or a CT scan.

Causes of diverticulosis

It is believed that diverticula result from high pressure inside the colon pushing out the inner lining through weak spots in the wall of the colon. Diets that are lower in fiber (or roughage) require the colon to generate more pressure to move the small, harder stools. Diets that contain enough fiber produce bulkier stool that moves easily through the colon without generating high pressures.

Symptoms of diverticulosis

In most people, there are no symptoms. Over time, some people may develop an infected diverticulum called diverticulitis (see below). This causes abdominal pain, tenderness, and fever. Diverticula can also cause bleeding from the rectum. Bleeding may be seen as red blood, maroon stools, or black tarry stool. Some patients may develop abdominal pain and alterations in bowel movements in the absence of infection. This is called painful diverticular disease and is actually due to irritable bowel syndrome. 

Frequency of diverticulosis and diverticulitis

Diverticulosis occurs in about 10% of people in their 40s and at least 50% of people by age 60. It is seen more frequently in older age groups. Only about 5-10% of diverticulosis patient ever develop diverticulitis, and only 3-4% develop bleeding due to diverticula. Diverticulosis is more common in developed countries, possibly due to a lower fiber diet. 

Prevention and treatment of diverticulosis

Avoiding constipation decreases the risk of developing or worsening diverticulosis:

--Eat a high-fiber diet, with whole grains, fruits (especially apples, pears, peaches, and plums), vegetables (especially carrots, broccoli, squash, spinach, and cauliflower), beans, peas, high-fiber cereals, whole wheat bread, brown rice, and nuts.

--Drink enough fluids (1-1/2 to 2 quarts per day, more in the summer) to keep your urine light yellow or clear.

--Exercise frequently.

--If necessary, take fiber supplements such as Metamucil, Citrucel, FiberCon, or Benefiber.

--Leave time each day for a bowel movement that is not rushed.


This disease occurs when a diverticulum becomes infected or inflamed. It usually causes lower abdominal pain and tenderness, most commonly on the left side, often with a change in bowel movements and sometimes fever or chills. Urinary symptoms or nausea and vomiting are occasionally present. There is typically tenderness when pressure is applied to the lower abdomen, especially on the left. 

Diagnosis of diverticulitis

Once diverticulitis is suspected, a CT scan of the abdomen and pelvis is the most commonly used diagnostic test. This establishes whether diverticulitis is actually present and also can check for complications such as abscesses (collections of pus) or spread of the infection outside the colon. Evidence of diverticulitis can also be seen on a barium enema x-ray. 

Treatment of diverticulitis

Outpatient (home) treatment: If the symptoms are mild or moderate, treatment with oral antibiotics and a clear liquid or low-fiber diet can be used. A low-fiber diet avoids whole grains, vegetables, and fruits, and is restricted to white starches (white rice, white bread, white potatoes without skin, and white pasta) and protein foods (meat, fish, seafood, poultry, eggs, and dairy products). However, you should contact your doctor for worsening or severe abdominal pain, fever (over 100.5°F), or inability to tolerate fluids by mouth.

Hospital treatment: If the symptoms are more severe, you may need to be admitted to the hospital for intravenous antibiotics and fluids, a very restricted diet, and close observation. If complications of diverticulitis develop, surgery is usually necessary. The complications include: 1. an abscess, which is a localized collection of pus in or adjacent to the wall of the colon (this can sometimes be treated by passing a thin tube through the skin to drain the pus); 2. a fistula, which is an abnormal tunnel or connection between two areas that are not normally connected (for example, the colon and the bladder); 3. obstruction (blockage) of the colon; and 4. peritonitis, in which the infection spreads beyond the colon into the spaces around the abdominal organs.

Surgery: If surgery becomes necessary, it usually involves removing the diseased portion of the colon. A temporary colostomy is frequently necessary; this is an opening from the colon out through the skin, where a bag is attached to collect stool from the colon. About 3 months later, a second operation is done to reconnect the intestine and close the colostomy opening in the skin. Even if there are no immediate complications of diverticulitis, surgery is sometimes necessary (usually without a colostomy) if there are frequent diverticulitis or bleeding attacks, if the infection does not completely resolve, or if there is bleeding that does not stop. Surgery greatly reduces the risk of further diverticulitis attacks. When the surgery is done without an active infection, the colostomy is often not necessary. 

What to do after a diverticulitis attack

Once the pain and tenderness have resolved, a normal diet is resumed. Most doctors suggest a [high fiber diet], which may prevent the development of new diverticula and is a healthy choice regardless. It is not necessary to avoid eating seeds, corn, and nuts, although this was often suggested in the past. Studies have shown that these foods do not affect the likelihood of further diverticulitis attacks.

After a first attack of diverticulitis, at least one-third of patients will eventually have another attack.

Colonoscopy is often recommended 2-3 months after an episode of diverticulitis to determine the extent of the diverticulosis and to exclude the presence of colon polyps or cancer.

To learn more about the treatment and diagnosis of diverticulosis and diverticulitis offered by Dr. Harary, please contact our New York City office.


Albert M. Harary, MD
110 East 55th Street, 17th Floor
Midtown East/Upper East Side

New York, NY 10022
Phone: 212-702-0123

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