Diverticulosis and Diverticulitis

A diverticulum is a out-pouching that can form in the wall of the colon usually  points where blood vessels enter the wall of the colon. Diverticulosis is the term for the presence of the out-pouchings when there are no symptoms. Diverticulitis is when there is inflammation or infection of the diverticula, causing pain and other symtoms.

Diverticular disease is a common problem that affects men and women equally. The incidence increases with age, affecting about 70% of people 70 years or older.  It occurs throughout the world but is seen more commonly in developed countries.



A person with diverticular disease may have diverticulosis, diverticulitis, or bleeding from diverticulosis.

Diverticulosis — Diverticulosis is often found with a test done for other reasons, such as flexible sigmoidoscopy, colonoscopy, or barium enema. Most people with diverticulosis have no symptoms and will remain symptom free for the rest of their lives. (See ‘Diverticular disease prognosis’ below.)

Diagram of the GI tract with diverticulosis in the colon

Diagram of the GI tract with diverticulosis in the colon

Diverticulitis — Inflammation of a diverticulum (diverticulitis) occurs when there is thinning of the diverticular wall. This may be caused by increased pressure within the colon or hardened particles of stool, which can become lodged within the diverticulum. Both of these events probably decrease blood flow to the diverticulum.

Diagram of the GI tract with diverticulosis in the colon



The symptoms of diverticulitis depend upon the degree of inflammation or infection present. The most common symptom is pain in the left lower abdomen. Other symptoms can also include nausea and vomiting, fever, constipation, diarrhea, and urinary symptoms.

Uncomplicated diverticulitis with an episode of pain, which accounts for 75 percent of cases, is not associated with complications and typically responds to medical treatment without surgery.

Complicated diverticulitis occurs in 25 percent of cases and usually requires surgery:

  • Abscess — Leakage of infection outside the colon causing a localized collection of pus
  • Fistula — an abnormal tract between two areas that are not normally connected (eg, bowel and bladder)
  • Obstruction — narrowing due to scarring causing blockage of the colon
  • Peritonitis — leakage of bowel contents directly into the abdominal cavity causing more diffuse and serious infection

Diverticular bleeding — Diverticula form at the area of insertion of a blood vessel into the colon. Bleeding occurs when these small arteries burst. Diverticular bleeding usually causes painless bleeding of red or maroon blood through rectum.



Diverticulosis is often found incidentally during tests performed for other reasons such as colonoscopy being done for colorectal cancer screening.

Diverticulosis in the colon as seen during colonoscopy

Diverticulosis in the colon as seen during colonoscopy

Mild diverticulitis can be tentatively diagnosed based on symptoms and physical exam.  CT scan provides additional information on the condition of the colon and can assess for the complications mentioned above. Colonoscopy can visualize inflammation directly in certain cases.

Diverticulosis in the colon as seen during colonoscopy


Diverticulosis — People with diverticulosis who do not have symptoms do not require treatment. Increasing fiber in the diet to 25grams or more daily can help to bulk the stools and possibly prevent the development of new diverticula, diverticulitis, or diverticular bleeding. Bulky stools require less colonic contraction pressure to move along, lower pressure may lead to less outpouching.

Seeds and nuts — Patients with diverticular disease have historically been advised to avoid seeds, corn, and nuts because of concern that these foods could lodge in a diverticulum and cause an episode of diverticulitis.  More recent studies have suggested that avoiding these items may actually have an increased risk of diverticulitis.  Currently, we recommend a high fiber diet that is chewed thoroughly and avoidance of anything that seems to cause symptoms in an individual person.

Mild diverticulitis – Mild symptoms of diverticulitis (mild abdominal pain, usually left lower abdomen) can be treated at home with initially a liquid diet and oral antibiotics. However, if you develop one or more of the following signs or symptoms, you should seek immediate medical attention:

Moderate to severe diverticulitis – High fever, inability to keep down liquids, worsening or severe abdominal pain, or complicated diverticulitis usually requires hospitalization and IV medications.

Complicated diverticulitis – An abscess would be drained under CT scan guidance. Surgery would be needed for blockage or peritonitis or fistula. Bleeding from diverticula is usually managed medically (blood transfusions etc.) as the bleeding will stop on its own 80% of the time. Surgery for bleeding is done if bleeding continues or recurs significantly.

Recurrent diverticulitis – After several recurrent episodes of diverticulitis, elective surgery can be don’t to remove the diseased area of the colon and reconnect the two ends of the colon without the need for a colostomy. Elective operations can usually be performed laparoscopically, using instruments passed thru small incisions, rather thru a longer vertical (up and down) abdominal incision.

After diverticulitis resolves – After an episode of diverticulitis resolves, the entire colon should be evaluated to determine the extent of disease and to rule out the presence of abnormal lesions such as polyps or cancer or Crohn’s disease with colonoscopy (unless colonoscopy has already been done within a reasonable time frame).

Preventing diverticulitis – There is no known way to prevent diverticulosis from becoming diverticulitis. Use of steroids, aspirin, or anti-inflammatory medications (ibuprofen, naproxen etc.) have been associated with recurrence of diverticulitis.  These medications may not be the cause but their use could be eliminated or modified, when possible.



About 15 to 25 percent of people with diverticulosis will develop diverticulitis while 5 to 15 percent will develop diverticular bleeding.

Diverticulitis — Approximately 85 percent of people with uncomplicated diverticulitis will respond to medical treatment while about 15 percent of patients will eventually need surgery. After successful treatment for a first attack of diverticulitis, one-third of patients will remain asymptomatic, one-third will have episodic cramps without diverticulitis, and one-third will go on to have a second attack of diverticulitis.

The prognosis is worse following a second attack of diverticulitis; the rate of complications in this group is close to 60 percent. Only 10 percent of people remain symptom free after a second attack.



  • Enjoy a high fiber low fat diet.
  • Use an additional supplemental fiber product (Metamucil, psyllium and others) if needed for a daily fiber intake of at least 25 grams.
  • Chew food thoroughly before swallowing.
  • It is not necessary to avoid certain foods such as corn or nuts, unless you notice that they both you.
  • In some patients, using steroids, aspirin, or anti-inflammatories (NSAID’s such as ibuprofen and naproxen and others) leads to a higher incidence of diverticulitis.