Diverticulosis 

and Diverticulitis 

National Digestive Diseases Information Clearinghouse 

U.S. Department 

of Health and 

Human Services 

NATIONAL 


INSTITUTES
 

OF HEALTH
 

What are diverticulosis and 

diverticulitis? 

Many people have small pouches in the lining of the colon, or large intestine, that bulge 

outward through weak spots. Each pouch is 

called a diverticulum. Multiple pouches are 

called diverticula. The condition of having 

diverticula is called diverticulosis. About 

10 percent of Americans older than 40 have 

diverticulosis.1 The condition becomes more 

common as people age. About half of all 

people older than 60 have diverticulosis.2 

Diverticula are most common in the lower 

portion of the large intestine, called the 

sigmoid colon. When the pouches become 

inflamed, the condition is called diverticulitis. 

Ten to 25 percent of people with diverticulosis 

get diverticulitis.3 Diverticulosis and diverticulitis together are called diverticular disease. 

What are the symptoms 

of diverticulosis and 

diverticulitis? 

Diverticulosis 

Most people with diverticulosis do not have 

any discomfort or symptoms. However, 

some people may experience crampy pain or 

discomfort in the lower abdomen, bloating, 

and constipation. Other conditions such as 

irritable bowel syndrome and stomach ulcers 

cause similar problems, so the symptoms do 

1Bogardus ST. What do we know about diverticular 


disease? A brief overview. Journal of Clinical 


Gastroenterology. 2006;40:S108–S111.
 2Ibid.
 

3Ibid.
 

Colon (large intestine) 

Diverticula 

Many people have small pouches in their colon that 

bulge outward through weak spots. Each pouch is 

called a diverticulum. Multiple pouches are called 

diverticula. The condition of having diverticula is 

called diverticulosis. 

not always mean a person has diverticulosis. 

People with chronic symptoms should visit 

their doctor or health care provider. 

Diverticulitis 

The most common symptom of diverticulitis 

is abdominal pain. The most common sign 

on examination is tenderness in the lower 

left side of the abdomen. Usually, the pain is 

severe and comes on suddenly, but it can also 

be mild and become worse over several days. 

The intensity of the pain can fluctuate. A person may experience cramping, nausea, vomiting, fever, chills, or a change in bowel habits. 
What are the complications 

of diverticulitis? 

Diverticulitis can lead to bleeding; infections; 

small tears, called perforations; or blockages 

in the colon. These complications always 

require treatment to prevent them from progressing and causing serious illness. 

Bleeding 

Rectal bleeding from diverticula is a rare 

complication. Doctors believe the bleeding 

is caused by a small blood vessel in a diverticulum that weakens and then bursts. When 

diverticula bleed, blood may appear in the 

toilet or in the stool. Bleeding can be severe, 

but it may stop by itself and not require treatment. A person who has bleeding from the 

rectum—even a small amount—should see 

a doctor right away. Often, colonoscopy is 

used to identify the site of bleeding and stop 

the bleeding. Sometimes the doctor injects 

dye into an artery—a procedure called 

angiography—to identify and treat diverticular bleeding. If the bleeding does not 

stop, surgery may be necessary to remove the 

involved portion of the colon. 

Abscess, Perforation, and 

Peritonitis 

Diverticulitis may lead to infection, which 

often clears up after a few days of treatment 

with antibiotics. If the infection gets worse, 

an abscess may form in the wall of the colon. 

An abscess is a localized collection of pus 

that may cause swelling and destroy tissue. 

If the abscess is small and remains in the wall 

of the colon, it may clear up after treatment 

with antibiotics. If the abscess does not clear 

up with antibiotics, the doctor may need to 

drain it using a catheter—a small tube— 

placed into the abscess through the skin. 

After giving the patient numbing medicine, 

the doctor inserts the needle through the skin 

until reaching the abscess and then drains the 

fluid through the catheter. This process may 

be guided by sonography or x ray. 

Infected diverticula may develop perforations. Sometimes the perforations leak pus 

out of the colon and form a large abscess 

in the abdominal cavity, a condition called 

peritonitis. A person with peritonitis may be 

extremely ill with nausea, vomiting, fever, and 

severe abdominal tenderness. The condition requires immediate surgery to clean the 

abdominal cavity and remove the damaged 

part of the colon. Without prompt treatment, 

peritonitis can be fatal. 

Fistula 

A fistula is an abnormal connection of tissue 

between two organs or between an organ and 

the skin. When damaged tissues come into 

contact with each other during infection, they 

sometimes stick together. If they heal that 

way, a fistula may form. When diverticulitisrelated infection spreads outside the colon, 

the colon’s tissue may stick to nearby tissues. 

The organs usually involved are the bladder, 

small intestine, and skin. 

The most common type of fi stula occurs 

between the bladder and the colon. This 

type of fistula affects men more often than 

women. It can result in a severe, long-lasting 

infection of the urinary tract. The problem 

can be corrected with surgery to remove the 

fistula and the affected part of the colon. 

Intestinal Obstruction 

Scarring caused by infection may lead to partial or total blockage of the intestine, called 

intestinal obstruction. When the intestine is 

blocked, the colon is unable to move bowel 

contents normally. If the intestine is completely blocked, emergency surgery is necessary. Partial blockage is not an emergency, 

so the surgery to correct it can be planned. 

2 Diverticulosis and Diverticulitis 
What causes diverticular 

disease? 

Although not proven, the dominant theory 

is that a low-fiber diet causes diverticular 

disease. The disease was first noticed in the 

United States in the early 1900s, around 

the time processed foods were introduced 

into the American diet. Consumption of 

processed foods greatly reduced Americans’ 

fiber intake. 

Diverticular disease is common in developed 

or industrialized countries—particularly 

the United States, England, and Australia—where low-fiber diets are consumed. 

The disease is rare in Asia and Africa, where 

most people eat high-fi ber diets. 

Fiber is the part of fruits, vegetables, and 

grains that the body cannot digest. Some 

fiber, called soluble fiber, dissolves easily in 

water. It takes on a soft, jelly-like texture in 

the intestines. Insoluble fiber passes almost 

unchanged through the intestines. Both 

kinds of fiber help prevent constipation by 

making stools soft and easy to pass. 

Constipation—or hard stool—may cause 

people to strain when passing stool during 

a bowel movement. Straining may cause 

increased pressure in the colon, which may 

cause the colon lining to bulge out through 

weak spots in the colon wall. These bulges 

are diverticula. 

Lack of exercise also may be associated 

with a greater risk of forming diverticula, 

although the reasons for this are not well 

understood. 

Doctors are not certain what causes diverticula to become inflamed. The infl ammation 

may begin when bacteria or stool are caught 

in the diverticula. An attack of diverticulitis 

can develop suddenly and without warning. 

How is diverticular disease 

diagnosed? 

To diagnose diverticular disease, the doctor 

asks about medical history, does a physical 

exam, and may perform one or more diagnostic tests. Because most people do not 

have symptoms, diverticulosis is often found 

through tests ordered for another ailment. 

For example, diverticulosis is often found 

during a colonoscopy done to screen for 

cancer or polyps or to evaluate complaints of 

pain or rectal bleeding. 

When taking a medical history, the doctor may ask about bowel habits, pain, other 

symptoms, diet, and medications. The 

physical exam usually involves a digital rectal 

exam. To perform this test, the doctor inserts 

a gloved, lubricated finger into the rectum to 

detect tenderness, blockage, or blood. The 

doctor may check stool for signs of bleeding 

and test blood for signs of infection. If diverticulitis is suspected, the doctor may order 

one of the following radiologic tests: 

•	 Abdominal ultrasound. Sound waves 

are sent toward the colon through 

a handheld device that a technician 

glides over the abdomen. The sound 

waves bounce off the colon and other 

organs, and their echoes make electrical 

impulses that create a picture—called 

a sonogram—on a video monitor. If 

the diverticula are inflamed, the sound 

waves will also bounce off of them, 

showing their location. 

•	 Computerized tomography (CT) scan. 

The CT scan is a noninvasive x ray that 

produces cross-section images of the 

body. The doctor may inject dye into 

a vein and the person may be given a 

similar mixture to swallow. The person 

lies on a table that slides into a donutshaped machine. The dye helps to show 

complications of diverticulitis such as 

perforations and abscesses. 

3 	 Diverticulosis and Diverticulitis 
How is diverticular disease 

treated? 

A high-fiber diet and pain medications help 

relieve symptoms in most cases of diverticulosis. Uncomplicated diverticulitis with mild 

symptoms usually requires the person to rest, 

take oral antibiotics, and be on a liquid diet 

for a period of time. Sometimes an attack 

of diverticulitis is serious enough to require 

a hospital stay, intravenous (IV) antibiotics, 

and possibly surgery. 

Diverticulosis 

Increasing the amount of fiber in the diet 

may reduce symptoms of diverticulosis and 

prevent complications such as diverticulitis. 

Fiber keeps stool soft and lowers pressure 

inside the colon so that bowel contents can 

move through easily. The American Dietetic 

Association recommends consuming 

20 to 35 grams of fiber each day. The table 

“What foods have fiber?” shows the amount 

of fiber in some foods that a person can easily add to the diet. 

The doctor may also recommend taking 

a fiber product such as methylcellulose 

(Citrucel) or psyllium (Metamucil) one to 

three times a day. These products are available in powder, pills, or wafers, and provide 

2 to 3.5 grams of fiber per dose. Fiber products should be taken with at least 8 ounces 

of water. 

Avoidance of nuts, popcorn, and sunfl ower, 

pumpkin, caraway, and sesame seeds has 

been recommended by physicians out of fear 

that food particles could enter, block, or irritate the diverticula. However, no scientifi c 

data support this treatment measure. Eating a high-fiber diet is the only requirement highly emphasized across the medical 

literature. Eliminating specific foods is not 

necessary. The seeds in tomatoes, zucchini, 

cucumbers, strawberries, and raspberries, as 

well as poppy seeds, are generally considered 

harmless. People differ in the amounts and 

types of foods they can eat. Decisions about 

diet should be made based on what works 

best for each person. Keeping a food diary 

may help identify what foods may cause 

symptoms. 

If cramps, bloating, and constipation are 

problems, the doctor may prescribe a short 

course of pain medication. However, some 

pain medications actually cause constipation. 

Diverticulitis 

Treatment for diverticulitis focuses on clearing up the inflammation and infection, resting the colon, and preventing or minimizing 

complications. 

Depending on the severity of symptoms, 

the doctor may recommend bed rest, oral 

antibiotics, a pain reliever, and a liquid diet. 

If symptoms ease after a few days, the doctor 

will recommend gradually increasing the 

amount of high-fiber foods in the diet. 

Severe cases of diverticulitis with acute 

pain and complications will likely require 

a hospital stay. Most cases of severe diverticulitis are treated with IV antibiotics and 

a few days without food or drink to help the 

colon rest. In some cases, surgery may be 

necessary. 

4 Diverticulosis and Diverticulitis 
What foods have fiber? 

Examples of foods that have fi ber include 

Breads, cereals, and beans Fiber 

1/2 cup of navy beans 9.5 grams 

1/2 cup of kidney beans 8.2 grams 

1/2 cup of black beans 7.5 grams 

Whole-grain cereal, cold 

1/2 cup of All-Bran 9.6 grams 

3/4 cup of Total 2.4 grams 

3/4 cup of Post Bran Flakes 5.3 grams 

1 packet of whole-grain cereal, hot 3.0 grams 

(oatmeal, Wheatena) 

1 whole-wheat English muffi n 4.4 grams 

Fruits 

1 medium apple, with skin 3.3 grams 

1 medium pear, with skin 4.3 grams 

1/2 cup of raspberries 4.0 grams 

1/2 cup of stewed prunes 3.8 grams 

Vegetables 

1/2 cup of winter squash 2.9 grams 

1 medium sweet potato with skin 4.8 grams 

1/2 cup of green peas 4.4 grams 

1 medium potato with skin 3.8 grams 

1/2 cup of mixed vegetables 4.0 grams 

1 cup of caulifl ower 2.5 grams 

1/2 cup of spinach 3.5 grams 

1/2 cup of turnip greens 2.5 grams 

Source: U.S. Department of Agriculture and U.S. Department of Health and Human 

Services, Dietary Guidelines for Americans, 2005. 

5 Diverticulosis and Diverticulitis 
When is surgery necessary 

for diverticulitis? 

If symptoms of diverticulitis are frequent, or 

the patient does not respond to antibiotics 

and resting the colon, the doctor may advise 

surgery. The surgeon removes the affected 

part of the colon and joins the remaining 

sections. This type of surgery—called colon 

resection—aims to prevent complications 

and future diverticulitis. The doctor may 

also recommend surgery for complications such as a fistula or partial intestinal 

obstruction. 

Immediate surgery may be necessary when 

the patient has other complications, such 

as perforation, a large abscess, peritonitis, 

complete intestinal obstruction, or severe 

bleeding. In these cases, two surgeries may 

be needed because it is not safe to rejoin the 

colon right away. During the fi rst surgery, 

the surgeon cleans the infected abdominal 

cavity, removes the portion of the affected 

colon, and performs a temporary colostomy, 

creating an opening, or stoma, in the abdomen. The end of the colon is connected to 

the opening to allow normal eating while 

healing occurs. Stool is collected in a pouch 

attached to the stoma. In the second surgery 

several months later, the surgeon rejoins the 

ends of the colon and closes the stoma. 

Points to Remember 

•	 Diverticulosis occurs when small 

pouches called diverticula bulge outward through weak spots in the colon, 

or large intestine. 

•	 Most people with diverticulosis never 

have any discomfort or symptoms. 

•	 Diverticula form when pressure builds 

inside the colon wall, usually because 

of constipation. 

•	 The most likely cause of diverticulosis 

is a low-fiber diet because it increases 

constipation and pressure inside the 

colon. 

•	 For most people with diverticulosis, 

eating a high-fiber diet is the only 

treatment needed. 

•	 Fiber intake can be increased by eating whole-grain breads and cereals; 

fruits like apples and pears; vegetables 

like peas, spinach, and squash; and 

starchy vegetables like kidney and 

black beans. 

•	 Diverticulitis occurs when the 

pouches become inflamed and cause 

pain and tenderness in the lower left 

side of the abdomen. 

•	 Diverticulitis can lead to bleeding; 

infections; small tears, called perforations; or blockages in the colon. 

These complications always require 

treatment to prevent them from progressing and causing serious illness. 

•	 Severe cases of diverticulitis with 

acute pain and complications will 

likely require a hospital stay. When a 

person has complications or does not 

respond to medication, surgery may 

be necessary. 

6 Diverticulosis and Diverticulitis 
Hope through Research 

The National Institute of Diabetes and 

Digestive and Kidney Diseases and the 

National Cancer Institute sponsor research 

programs to investigate diverticulosis and 

diverticulitis. 

Investigation continues in several areas, 

including 

•	 a possible link between diverticular disease and inflammatory bowel disease 

•	 the management of recurrent diverticular disease 

•	 the use of probiotics in the prevention 

and treatment of diverticular disease 

•	 indications for surgery for uncomplicated diverticulitis 

Participants in clinical trials can play 

a more active role in their own health care, 

gain access to new research treatments 

before they are widely available, and help 

others by contributing to medical research. 

For information about current studies, visit 

www.ClinicalTrials.gov. 

For More Information 

American College of Gastroenterology 

P.O. Box 342260 

Bethesda, MD 20827–2260 

Phone: 301–263–9000 

Fax: 301–263–9025 

Internet: www.acg.gi.org 

American Gastroenterological 

Association 

4930 Del Ray Avenue 

Bethesda, MD 20814 

Phone: 301–654–2055 

Fax: 301–654–5920 

Email: member@gastro.org 

Internet: www.gastro.org 

American Society of Colon and Rectal 

Surgeons 

85 West Algonquin Road, Suite 550 

Arlington Heights, IL 60005 

Phone: 847–290–9184 

Fax: 847–290–9203 

Email: ascrs@fascrs.org 

Internet: www.fascrs.org 

International Foundation for Functional 

Gastrointestinal Disorders 

P.O. Box 170864 

Milwaukee, WI 53217–8076 

Phone: 1–888–964–2001 

 or 414–964–1799 

Fax: 414–964–7176 

Email: iffgd@iffgd.org 

Internet: www.iffgd.org 

7 	 Diverticulosis and Diverticulitis 
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U.S. DEPARTMENT OF HEALTH 

AND HUMAN SERVICES

National Institutes of Health

NIH Publication No. 08–1163

July 2008