Diverticula are small, bulging pouches that can form in the lining of your digestive system. They are found most often in the lower part of the large intestine (colon). Diverticula are common, especially after age 40, and seldom cause problems.

The presence of diverticula is known as diverticulosis (die-vur-tik-yoo-LOE-sis). When one or more of the pouches become inflamed, and in some cases infected, that condition is known as diverticulitis (die-vur-tik-yoo-LIE-tis). Diverticulitis can cause severe abdominal pain, fever, nausea and a marked change in your bowel habits.

Mild diverticulitis can be treated with rest, changes in your diet and antibiotics. Severe or recurring diverticulitis may require surgery.

The signs and symptoms of diverticulitis include:

• Pain, which may be constant and persist for several days. The lower left side of the abdomen is the usual site of the pain. Sometimes, however, the right side of the abdomen is more painful, especially in people of Asian descent.
• Nausea and vomiting.
• Fever.
• Abdominal tenderness.
• Constipation or, less commonly, diarrhea.

When to see a doctor

Get medical attention anytime you have constant, unexplained abdominal pain, particularly if you also have a fever and constipation or diarrhea.

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.

Diverticulitis occurs when diverticula tear, resulting in inflammation, and in some cases, infection.

Several factors may increase your risk of developing diverticulitis:

• Aging. The incidence of diverticulitis increases with age.
• Obesity. Being seriously overweight increases your odds of developing diverticulitis.
• Smoking. People who smoke cigarettes are more likely than nonsmokers to experience diverticulitis.
• Lack of exercise. Vigorous exercise appears to lower your risk of diverticulitis.
• Diet high in animal fat and low in fiber. A low-fiber diet in combination with a high intake of animal fat seems to increase risk, although the role of low fiber alone isn't clear.
• Certain medications. Several drugs are associated with an increased risk of diverticulitis, including steroids, opioids and nonsteroidal anti-inflammatory drugs, such as ibuprofen (Advil, Motrin IB, others) and naproxen sodium (Aleve).

About 25% of people with acute diverticulitis develop complications, which may include:

• An abscess, which occurs when pus collects in the pouch.
• A blockage in your bowel caused by scarring.
• An abnormal passageway (fistula) between sections of bowel or the bowel and other organs.
• Peritonitis, which can occur if the infected or inflamed pouch ruptures, spilling intestinal contents into your abdominal cavity. Peritonitis is a medical emergency and requires immediate care.

To help prevent diverticulitis:

• Exercise regularly. Exercise promotes normal bowel function and reduces pressure inside your colon. Try to exercise at least 30 minutes on most days.
• Eat more fiber. A high-fiber diet decreases the risk of diverticulitis. Fiber-rich foods, such as fresh fruits and vegetables and whole grains, soften waste material and help it pass more quickly through your colon. Eating seeds and nuts isn't associated with developing diverticulitis.
• 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.
• Avoid smoking. Smoking is associated with an increased risk of diverticulitis.

Diverticulitis is usually diagnosed during an acute attack. Because abdominal pain can indicate a number of problems, your doctor will need to rule out other causes for your symptoms.

Your doctor will start with a physical examination, which will include checking your abdomen for tenderness. Women generally have a pelvic examination as well to rule out pelvic disease.

After that, the following tests are likely:

• Blood and urine tests, to check for signs of infection.
• A pregnancy test for women of childbearing age, to rule out pregnancy as a cause of abdominal pain.
• A liver enzyme test, to rule out liver-related causes of abdominal pain.
• A stool test, to rule out infection in people who have diarrhea.
• A CT scan, which can identify inflamed or infected pouches and confirm a diagnosis of diverticulitis. CT can also indicate the severity of diverticulitis and guide treatment.

Treatment depends on the severity of your signs and symptoms.

Uncomplicated diverticulitis

If your symptoms are mild, you may be treated at home. Your doctor is likely to recommend:

• Antibiotics to treat infection, although new guidelines state that in very mild cases, they may not be needed.
• A liquid diet for a few days while your bowel heals. Once your symptoms improve, you can gradually add solid food to your diet.

This treatment is successful in most people with uncomplicated diverticulitis.

Complicated diverticulitis

If you have a severe attack or have other health problems, you'll likely need to be hospitalized. Treatment generally involves:

• Intravenous antibiotics
• Insertion of a tube to drain an abdominal abscess, if one has formed

Surgery

You'll likely need surgery to treat diverticulitis if:

• You have a complication, such as a bowel abscess, fistula or obstruction, or a puncture (perforation) in the bowel wall
• You have had multiple episodes of uncomplicated diverticulitis
• You have a weakened immune system

There are two main types of surgery:

• Primary bowel resection. The surgeon removes diseased segments of your intestine and then reconnects the healthy segments (anastomosis). This allows you to have normal bowel movements. Depending on the amount of inflammation, you may have open surgery or a minimally invasive (laparoscopic) procedure.
• Bowel resection with colostomy. If you have so much inflammation that it's not possible to rejoin your colon and rectum, the surgeon will perform a colostomy. An opening (stoma) in your abdominal wall is connected to the healthy part of your colon. Waste passes through the opening into a bag. Once the inflammation has eased, the colostomy may be reversed and the bowel reconnected.

Follow-up care

Your doctor may recommend colonoscopy six weeks after you recover from diverticulitis, especially if you haven't had the test in the previous year. There doesn't appear to be a direct link between diverticular disease and colon or rectal cancer. But colonoscopy — which is risky during a diverticulitis attack — can exclude colon cancer as a cause of your symptoms.

After successful treatment, your doctor may recommend surgery to prevent future episodes of diverticulitis. The decision on surgery is an individual one and is often based on the frequency of attacks and whether complications have occurred.

Some experts suspect that people who develop diverticulitis may not have enough good bacteria in their colons. Probiotics — foods or supplements that contain beneficial bacteria — are sometimes suggested as a way to prevent diverticulitis. But that advice hasn't been scientifically validated.

You may be referred to a doctor who specializes in disorders of the digestive system (gastroenterologist).

What you can do

• Be aware of any pre-appointment restrictions, such as not eating solid food on the day before your appointment.
• Write down your symptoms, including any that may seem unrelated to the reason why you scheduled the appointment.
• Make a list of all your medications, vitamins and supplements.
• Write down your key medical information, including other conditions.
• Write down key personal information, including any recent changes or stressors in your life.
• Ask a relative or friend to accompany you, to help you remember what the doctor says.
• Write down questions to ask your doctor.

Questions to ask your doctor

• What's the most likely cause of my symptoms?
• What kinds of tests do I need? Do these tests require any special preparation?
• What treatments are available?
• Will the diverticulitis come back?
• Should I remove or add any foods in my diet?
• I have other health conditions. How can I best manage these conditions together?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask other questions during your appointment.

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may make time to go over points you want to spend more time on. You may be asked:

• When did you first begin experiencing symptoms, and how severe are they?
• Have your symptoms been continuous or occasional?
• What, if anything, seems to improve or worsen your symptoms?
• Have you had a fever?
• What medications and pain relievers do you take?
• Have you had any pain with urination?
• Have you ever had a screening test for colon cancer (colonoscopy)?