Diverticulitis

Diverticulitis is inflammation or infection of one or more diverticula.

Diverticulitis occurs in people with diverticulosis. It most commonly affects the sigmoid colon, which is the last part of the large intestine just before the rectum. Diverticulitis is more common in people older than 40. It can be severe in people of any age, although it is most serious in the elderly, especially those taking corticosteroids or other drugs that suppress the immune system and thus increase the hazards of infection. Among people younger than 50 who must undergo surgery for diverticulitis, men outnumber women three to one; among those older than 70, women outnumber men three to one.

Symptoms and Diagnosis

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

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

A CT or ultrasound scan may be helpful for determining that the problem is diverticulitis and not appendicitis or an abscess.

Once inflammation has subsided or infection has been treated, a doctor may perform a colonoscopy (an examination of the large intestine using a flexible viewing tube) or a barium enema x-ray study. These tests are performed to either confirm the presence or assess the severity of diverticula. 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 may be needed to confirm the diagnosis.

Complications

The inflammation of the intestinal wall 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 penetrates the adjacent organ, resulting in a fistula. Most fistulas form between the sigmoid colon and the bladder. These fistulas are more common in men than in 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 or chest.

See the figure Complications of Diverticular Disease.

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 pus-filled pocket of infection), infection of the lining of the abdominal cavity (peritonitis), and bleeding. Repeated bouts of diverticulitis can lead to intestinal obstruction, because the resulting scarring and muscle thickening can narrow the inside of the large intestine and prevent solid stool from passing through.

Treatment

Mild diverticulitis can be treated with rest, a liquid diet, and oral antibiotics. Symptoms usually disappear rapidly. After a few days, the person can begin a soft, low-fiber diet and take a daily psyllium seed preparation. After 1 month, a high-fiber diet can be started.

People with more severe 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 generally admitted to the hospital. There they are given intravenous fluids and antibiotics, kept on bedrest, and given nothing by mouth until the symptoms subside. About 20% of people who have diverticulitis require surgery because the condition does not improve.

If the source of bleeding is known, only the affected section of the intestine is removed, in most people. If the source of bleeding is not known, a larger section of the intestine is removed in a procedure called subtotal colectomy.

Emergency surgery is necessary for people whose intestine has ruptured; intestinal rupture always results in infection of the abdominal cavity. The surgeon generally removes the ruptured section and creates an opening between the large intestine and the skin surface. This opening is called a colostomy (see Section 9, Chapter 131). About 10 to 12 weeks later (or sometimes longer), the cut ends of the intestine are rejoined during a follow-up operation, and the colostomy is closed.

Surgery may be optional for some people with diverticulitis. If an abscess is discovered, draining it through the skin might be attempted before surgery is considered.

Treatment of a fistula 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).

See the table Diverticulitis: Reasons for Elective Surgery.