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It's common for people older than age 60 to have small, bulging pouches (diverticula) in their digestive tracts — a condition known as diverticulosis. Although diverticula can form anywhere, including in your esophagus, stomach and small intestine, most occur in your large intestine. Because these pouches seldom cause any problems, you may never know you have them.

Sometimes, however, one or more pouches becomes inflamed or infected, causing severe abdominal pain, fever, nausea and a marked change in your bowel habits. When diverticula become infected, the condition is called diverticulitis. Mild cases of diverticulitis can be treated with rest, changes in your diet and antibiotics. But serious cases may require surgery to remove the diseased portion of your colon.

Fortunately, most people with diverticulosis never develop diverticulitis. Best of all, you can help prevent both types of diverticular disease by including more high-fiber foods in your diet.

Diverticulitis can feel like appendicitis, except you'll generally have pain in the lower left side of your abdomen, instead of the lower right side. The pain is usually severe and comes on suddenly, but sometimes you may have mild pain that becomes worse over several days and fluctuates in intensity. You may also have abdominal tenderness, fever, nausea, and constipation or diarrhea.

Less common signs and symptoms of diverticulitis may include:

• Vomiting
• Bloating
• Bleeding from your rectum
• Frequent urination
• Difficulty or pain while urinating
• Tenderness in your abdomen when wearing a belt or bending over

Diverticula usually develop when naturally weak places in your colon give way under pressure. This causes marble-sized pouches to protrude through the colon wall. Pouches are most common in your sigmoid and descending colon — the lower portions of your large intestine just above your rectum — and often occur as a result of straining during bowel movements over a number of years. The pouches are small at first but become larger with time.

Sometimes a bit of stool may become lodged in one of the pouches, leading to infection. A small tear or perforation can also develop in an infected pouch, which in turn can cause an infection within your abdomen (peritonitis). If the infection is limited to an area around the wall of your colon where the diverticula are inflamed, you may develop a localized collection of pus known as an abscess.

These factors may increase the pressure on the wall of your colon:

• Aging. As you age, the outer muscular wall of your colon thickens, causing the inside passageway to narrow. The narrowing increases pressure in your colon and makes it more likely that pouches will form. Thickening of the outer wall also makes it more difficult for your colon to move waste through to your rectum. This means waste stays in your colon longer, becoming harder and dryer and exerting additional pressure on weak areas when the muscles of your colon try to move it along.
• Too little fiber. Diverticulitis is rare in countries where people eat a high-fiber diet that helps keep stools soft. But it's common in industrialized nations, such as the United States, where the average diet is high in refined carbohydrates and low in fiber. In fact, diverticular disease emerged after the introduction of steel rolling mills, which greatly reduced the fiber content of flour and other grains. The disease was first observed in the United States in the early 1900s, around the time processed foods became a mainstay of the American diet. Too little fiber contributes to small, hard stools that are difficult to pass, which increases pressure in your colon.

Because diverticula by themselves usually don't cause problems, most people learn they have diverticulosis during routine screening examinations for colorectal cancer or during tests that check for other intestinal problems. Diverticulitis, on the other hand, is usually diagnosed during an acute attack. Your doctor is likely to examine your abdomen for tenderness. You may also have a blood test to check your white blood cell count and an imaging test such as a CT scan to help visualize the pouches that are inflamed or infected. A CT scan uses a series of computer-directed X-rays to provide a comprehensive view of your internal organs. Diverticulitis can range from minor inflammation to a massive infection. Because diverticulitis can be serious, see your doctor right away if you suspect you're having an attack.

In rare cases, an infected or inflamed pouch may rupture, spilling intestinal waste into your abdomen and leading to peritonitis — an inflammation of the lining of your abdominal cavity (peritoneum). Peritonitis is a medical emergency and requires immediate care.

Other complications of diverticulitis may include a blockage in your colon or small intestine, an abscess or a fistula. A fistula is an abnormal passageway that occurs between different parts of your intestine, your intestine and your bladder or vagina, or your intestine and abdominal wall. Sometimes fistulas themselves become infected — a condition that can be life-threatening if left untreated.

Although there's no evidence that diverticular disease increases your risk of colon or rectal cancer, it can make cancer more difficult to diagnose. Because of this, your doctor may recommend a colonoscopy after you've recovered from a bout of diverticulitis along with more frequent cancer-screening tests. A colonoscopy is a test that allows your doctor to examine your entire colon and rectum for abnormalities using a long, flexible tube with a tiny video camera at the tip (colonoscope).

In general, treatment depends on the severity of your symptoms and whether this is your first attack of diverticulitis. If your symptoms are mild, a liquid or low-fiber diet and antibiotics may be all you need. But if you're at risk of complications or have recurrent attacks of diverticulitis, you may need more advanced care.

Home care
If your condition calls for home treatment, expect to remain quiet for a few days. You'll also temporarily need to avoid all whole grains, fruits and vegetables so that your colon can rest and heal. Once your symptoms improve — often in two to four days — you can gradually start increasing the amount of high-fiber foods in your diet.

In addition, your doctor will likely prescribe antibiotics to help kill the bacteria causing your infection. Even if you start feeling better, be sure to finish your entire course of medication. Stopping too soon could cause your infection to come back. It also helps create strains of bacteria that are resistant to antibiotics.

If you have moderate or severe pain, your doctor may recommend an over-the-counter pain reliever such as acetaminophen (Tylenol, others). Your doctor may also prescribe a more potent pain medication, although these medications tend to be constipating and may aggravate the problem.

Hospitalization
About half the people with diverticulitis require hospitalization and many need intravenous antibiotics. You're more likely to be hospitalized if you have vomiting, a fever above 100 F, a high white blood cell count or are at risk of complications such as a bowel obstruction or peritonitis. You're also likely to need additional care if you are older, have another disease or have a weakened immune system.

Surgery
If you have recurring diverticulitis, your doctor may recommend surgery to remove the diseased part of your colon. There are two types of surgery:

• Primary bowel resection. This is the standard surgery for people with diverticulitis. Your surgeon removes the diseased part of your intestine and then reconnects the healthy segments of your colon (anastomosis). This allows you to have normal bowel movements. Depending on the amount of inflammation, you may have open (traditional) surgery or laparoscopic surgery. In open surgery, your surgeon makes one long incision in your abdomen, while laparoscopic surgery is performed through three or four tiny incisions. You'll heal faster and recover more quickly with laparoscopic surgery. It may not be an option if you are very overweight or have extensive inflammation.
• Bowel resection with colostomy. This surgery may be necessary if you have so much inflammation in your colon that it's not possible to rejoin your colon and rectum. During a colostomy, your surgeon makes an opening (stoma) in your abdominal wall. The unaffected part of your colon is then connected to the stoma, and waste passes through the opening into a bag. A colostomy may be temporary or permanent. Several months later — once the inflammation has healed — your surgeon may be able to perform a second operation to reconnect your colon and rectum.

Some measures can help prevent or slow the progression of diverticular disease:

• Eat more fiber. High-fiber foods, such as fresh fruits and vegetables and whole grains, soften waste material and help it pass more quickly through your colon. This reduces pressure inside your digestive tract. Aim for 25 to 30 grams of fiber each day. Try to substitute fruits, vegetables and grain products for foods high in fat. Be sure to add fiber gradually to avoid bloating, abdominal discomfort and gas. If you have a hard time consuming 25 to 30 grams of fiber every day, consider using a fiber supplement such as psyllium (Metamucil, Nature's Way) or methylcellulose (Citrucel).
• Drink plenty of fluids. Fiber works by absorbing water and increasing the soft, bulky waste in your colon. But if you don't drink enough liquid to replace what's absorbed, fiber can be constipating.
• Respond to bowel urges. When you need to use the bathroom, don't delay. Delaying bowel movements leads to harder stools that require more force to pass and increased pressure within your colon.
• Exercise regularly. Exercise promotes normal bowel function and reduces pressure inside your colon. Try to exercise at least 30 minutes on most days.