Diverticulosis and diverticulitis are found most often in affluent industrialized countries, where low-fiber diets are popular. Here’s discussion of this common condition.

As we age, most of us develop small pouches (diverticula) that bulge outward through weak points in the wall of the large intestine -- a condition termed diverticulosis. The condition is present in about half of Americans between the ages of 60 and 80, and in virtually everyone older than 80. A disorder called diverticulitis, an infection or inflammation of the diverticula, develops in about 10% to 25% of people with diverticulosis. Diverticulosis and diverticulitis together are sometimes referred to as diverticular disease.

What causes diverticulosis and diverticulitis?

A low-fiber diet is believed to be a major culprit in diverticulosis because it leads to constipation. The increased pressure inside the colon resulting from straining to move hardened stool can cause weak spots in the colon wall to bulge outward and become diverticula.

Interestingly, diverticulosis primarily affects people in affluent industrialized countries, where low-fiber diets are common. The highest incidence of the disease occurs in the United States, Europe, and Australia. By contrast, diverticulosis is extremely rare in rural regions of Africa or Asia, where people consume high-fiber, vegetable- rich diets.

Diverticulitis is thought to occur when bacteria or hardened stool trapped in a diverticulum gives rise to infection or inflammation. This process may ultimately lead to a perforation, the formation of a small hole in the tip of a diverticulum, which allows bacteria to enter the abdomen. The resulting infection may be localized (abscess) or generalized (peritonitis).

Symptoms of diverticulosis and diverticulitis

Although most individuals with diverticulosis have no discomfort or symptoms, some experience mild abdominal pain, bloating, and constipation. The pain typically occurs in the lower abdomen, most often on the left side. A physical examination may reveal fullness or tenderness in this area.

Attacks of diverticulitis can occur suddenly and without warning. The most common symptom of diverticulitis is pain in the lower left side of the abdomen. Other symptoms of diverticulitis may include fever, nausea, vomiting, chills, constipation, diarrhea, painful or difficult urination, and increased frequency of urination. The severity of diverticulitis symptoms depends on the extent of the infection and the presence of any complications.

Diagnosis of diverticulosis and diverticulitis

In patients without symptoms, diverticulosis is often discovered during a diagnostic exam, such as a barium enema x-ray, sigmoidoscopy, or colonoscopy, for another gastrointestinal ailment. In a patient whose symptoms, medical history, and physical examination suggest diverticular disease, the physician carries out one or more diagnostic tests. Often a barium enema x-ray or a computed tomography (CT) scan are used to diagnose diverticular disease and its complications.

Because diverticular disease and colon cancer share many symptoms and are both common in elderly individuals, it is important to distinguish between the two. Colonoscopy has proved most useful in differentiating between diverticular disease and colon cancer. Some doctors recommend routine colonoscopy to exclude cancer in any individual experiencing the symptoms of diverticular disease.

Potential complications of diverticulosis and diverticulitis

Complications of diverticular disease include bleeding, abscess formation and peritonitis, and formation of a fistula. If untreated, such complications may cause serious illness and even death.

• Bleeding. Diverticula may occasionally bleed. Between 15% and 40% of people with diverticulosis experience painless bleeding from the rectum; massive bleeding occurs in only about 5% of people with diverticulosis.
• Abscess formation and peritonitis. If appropriate antibiotic therapy does not eradicate the infection associated with diverticulitis, an abscess may form in the abdominal cavity adjacent to the colon.
• Fistula. A fistula is an abnormal connection between two organs. In diverticulitis, fistulas can form when an abscess erodes and establishes a passage between the colon and an adjacent organ.

Treatment of diverticulosis and diverticulitis

For most people with diverticulosis, eating a high-fiber diet is the only treatment required. This approach may decrease the symptoms of diverticulosis and prevent the development of diverticulitis. By making the stools softer and bulkier, certain types of fiber, such as wheat bran, decrease pressure in the colon and allow the bowel contents to move through more easily. A daily intake of 20 to 35 g of fiber is generally recommended. Your doctor may also suggest drinking a fiber product such as Citrucel or Metamucil: A single dose (one teaspoon or tablespoon, depending on the product) mixed with an 8-oz glass of water provides 2 to 3.4 g of fiber.

Diverticulitis is usually treated at home with bed rest, a liquid diet to rest the colon, and oral antibiotics. Individuals with severe diverticulitis may be hospitalized and treated with intravenous antibiotics. About 80% of people with severe diverticulitis can be treated successfully without surgery.