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Diverticulitis -ˈlīt-əs

By Michael C. DiMarino, MD, Clinical Assistant Professor, Sidney Kimmel Medical College at Thomas Jefferson University

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Diverticulitis is inflammation or infection of one or more balloon-like sacs (diverticula).

  • Diverticulitis usually affects the colon.

  • Left lower abdominal pain, tenderness, and fever are the typical diverticulitis symptoms.

  • The diagnosis is based on the results of a computed tomography scan and is confirmed later by colonoscopy.

  • People with mild diverticulitis symptoms are treated with rest, a liquid diet, and often oral antibiotics, whereas those with severe symptoms are hospitalized for treatment with intravenous antibiotics and sometimes surgery.

Diverticulitis occurs in people with diverticulosis. This disorder occurs when a diverticulum develops a small hole that allows bacteria from the intestines to be released. Diverticulitis most commonly affects the sigmoid colon, which is the last part of the large intestine just before the rectum. Diverticulitis is more common among people older than 40. It can be severe in people of any age, although it is most serious in older people, especially those taking corticosteroids or other drugs that suppress the immune system and thus increase the risk of infection, including colon infection. Among people younger than 50 who must undergo surgery for diverticulitis, men outnumber women 3 to 1. Among people older than 70 who must undergo surgery for diverticulitis, women outnumber men 3 to 1.

Symptoms of Diverticulitis

Diverticulitis typically causes pain or tenderness (usually in the left lower part of the abdomen) and fever. Unlike diverticulosis, diverticulitis typically does not cause gastrointestinal bleeding.

Complications of diverticulitis

Intestinal inflammation can lead to the development of fistulas (abnormal channels) that connect the large intestine with other organs. Fistulas usually form when a diverticulum in the large intestine is touching another organ (such as the bladder) and the diverticulum ruptures. The resulting inflammation along with the bacterial contents of the large intestine slowly penetrate the nearby organ, resulting in a fistula. Most fistulas form between the sigmoid colon and the bladder. These fistulas are more common among men than women, although women who have had a hysterectomy (removal of the uterus) are at increased risk because the large intestine and bladder are no longer separated by the uterus. When fistulas form between the large intestine and bladder, intestinal contents, including normal bacteria, enter the bladder and cause urinary tract infections. Less commonly, a fistula can develop between the large intestine and the small intestine, uterus, vagina, abdominal wall, or even the thigh.

Complications of Diverticular Disease

In diverticular disease, a diverticulum may bleed into the intestine. If a diverticulum ruptures, the contents of the intestine, including bacteria and blood, spill into the abdominal cavity, often causing infection. An abnormal channel (fistula) may form between the large intestine and another organ, usually when a diverticulum that touches another organ ruptures.

Other possible complications of diverticulitis include inflammation of nearby organs (such as the uterus, bladder, or other areas of the digestive tract), rupture of the wall of a diverticulum, abscess (a pocket of pus), and infection of the lining of the abdominal cavity (peritonitis). Repeated bouts of diverticulitis can lead to intestine blockage because the resulting scarring and muscle thickening can narrow the inside of the large intestine and prevent solid stool from passing through.

Diagnosis of Diverticulitis

If a doctor knows that the person already has diverticulosis, a diverticulitis diagnosis may be based almost entirely on the symptoms. However, many other conditions involving the large intestine and other organs in the abdomen and pelvis can cause symptoms similar to diverticulitis, including appendicitis, colon or ovarian cancer, an abscess, and noncancerous (benign) growths on the wall of the uterus (uterine fibroids).

A computed tomography (CT) scan of the abdomen may be helpful in determining that the problem is diverticulitis and not appendicitis or an abscess.

Once inflammation has subsided or the infection has been treated, a doctor does a colonoscopy (an examination of the large intestine using a flexible viewing tube) or a barium enema x-ray study. These tests are done to confirm the presence and assess the severity of diverticula and to rule out colon cancer. Colonoscopy or barium enema x-rays usually need to be delayed for several weeks after treatment because they could damage or rupture an inflamed intestine. Exploratory surgery is rarely needed to confirm the diagnosis.

Treatment of Diverticulitis

Mild diverticulitis can be treated at home with rest, a liquid diet, and oral antibiotics (such as ciprofloxacin). Diverticulitis symptoms usually lessen rapidly. Some people may not need antibiotics for diverticulitis. After a few days, people can begin a soft, low-fiber diet for 4 to 6 weeks. After 6 to 8 weeks, people have a colonoscopy or a barium enema to evaluate the colon. After 1 month, a high-fiber diet can be started.

People with more severe diverticulitis symptoms—such as abdominal pain, body temperature above 101° F (38.3° C), poor response to oral antibiotics, and other evidence of serious infection or complications—are hospitalized. In the hospital, people are given fluids and antibiotics by vein (intravenously), kept on bed rest, and given nothing by mouth until the symptoms subside.

About 80% of people can be treated without surgery for diverticulitis. An abscess is drained with a needle inserted through the skin and guided by a CT scan. If drainage helps, people remain in the hospital until symptoms have been relieved and they have resumed a soft diet.

Surgery for Diverticulitis

Emergency surgery is necessary for people whose intestine has ruptured, or who have peritonitis and for people with severe diverticulitis symptoms that do not respond to nonsurgical treatment within 48 hours. People who have increasing pain, tenderness, and fever also need surgery.

Intestinal rupture always results in infection of the abdominal cavity. The surgeon removes the ruptured section of the intestine. The ends are rejoined immediately in healthy people who do not have a perforation, abscess, or severe intestinal inflammation. Other people need a temporary colostomy (see see Figure: Understanding Colostomy). A colostomy is an opening between the large intestine and the skin surface. About 10 to 12 weeks later (or sometimes longer), after the inflammation has gone away and the person's condition has improved, the cut ends of the intestine are rejoined during a follow-up operation, and the colostomy is closed.

Fistula treatment involves removing the section of large intestine where the fistula begins, rejoining the cut ends of the large intestine, and repairing the other affected area (for example, the bladder or small intestine).

Diverticulitis: Reasons for Elective Surgery



Three or more attacks of mild diverticulitis (or one attack in someone younger than 50)

High risk of serious complications

Narrowing of the sigmoid colon (lower part of the large intestine) due to scarring

High risk of serious complications

Persistent tender mass in the abdomen

May be cancer

Endoscopy or x-rays showing suspicious changes in the sigmoid colon

May be cancer

Pain when urinating (dysuria) or air in the urine (pneumaturia)

May be a warning of impending fistula formation between the large intestine and the bladder

Sudden abdominal pain in people taking corticosteroids

Large intestine may have ruptured into the abdominal cavity

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