The Facts

Diverticula are sacs formed by a fold of the lining of the intestinal wall. They extend through the muscle surrounding the bowel, and occasionally trap feces moving through the intestine may divert into them and become trapped. Diverticula are extremely common and usually harmless. They tend to appear after age 40 and are more likely to appear in seniors.

Diverticulosis is the condition of having one or more diverticula. Usually there are no symptoms or problems associated with this condition.

Occasionally, diverticula become inflamed. If you have one or more inflamed diverticula, you are diagnosed with diverticulitis. The word ending "-itis" means inflammation. Diverticulitis can be a serious condition.

Diverticula often appear in bunches. Each is typically less than an inch in diameter. Rare giant diverticula can be up to 6 inches in diameter, and always appear alone.

Diverticula can also appear in the gastrointestinal tract above the stomach, in the esophagus. In these cases, it's food rather than feces that may get trapped. Esophageal diverticula don't cause dangerous problems, but a few people find that trapped food comes back up when they bend over or lie down.


It's believed that most diverticula are caused by unnoticed muscle spasms, or by pairs of muscles that don't contract in a synchronized manner. This puts brief but intense pressure on the mucosal layer, causing pressure at the weakest points. The weakest points are the areas around blood vessels that pass through the inside of the wall of the large intestine (also called the colon). Older people have frailer tissue lining the bowel – this is probably why they have more diverticula.

Nobody is sure what causes giant diverticula. One popular theory is that a hole in the mucosal layers acts as a valve. It lets bowel gas in but not out, inflating the tissue like a balloon.

Factors which may increase your chance of developing diverticula include a low-fibre diet and lack of exercise. Being overweight can also increase the risk of developing diverticulitis.

Symptoms and Complications

Diverticulosis is unnoticeable if there are no complications. Most people live their whole lives without their diverticula ever becoming noticeable.

Bleeding and inflammation are two possible complications of diverticulosis.

Bleeding can result if feces get lodged in a diverticulum. The bowel draws fluid out of feces before ejecting it. If it stays there a long time, it becomes dry and hard. It can erode nearby blood vessels. Occasionally a large amount of bright red blood comes out of the rectum. If heavy bleeding continues, it's an emergency requiring immediate hospital treatment. If a very small amount leaks out continually, it can still add up over time and cause mild anemia. Bleeding that doesn't stop always requires treatment.

The other potential problem caused by diverticula is inflammation – in other words, diverticulitis. Unlike bleeding diverticula, inflamed and infected diverticula can become extremely painful. Sudden pain is particularly bad in the lower left abdomen, as most diverticula occur in the left side of the bowel. Pressing this area gently will make the discomfort worse. You may also experience nausea and vomiting, changes in bowel habits, and potential difficulty or pain while passing urine. You might also run a fever.

Diverticulitis can range from being mildly uncomfortable to dangerous. It depends on the amount of inflammation in the bowels. A fistula is a tunneling inflammation that eats its way from one organ to another. Organs near the bowel (e.g., the bladder, uterus, and vagina) can be affected. If the inflammation eats through the bowel wall or if the bowels are perforated, stool can spill into the abdominal cavity. The resulting infection and inflammation creates a serious situation known as peritonitis. Peritonitis is the name used when large parts of the abdominal cavity are inflamed. People with peritonitis always have a fever, and the belly often feels hard and bloated. Untreated, peritonitis causes death in a few hours or days.

Making the Diagnosis

One way to find diverticula is with a barium enema X-ray. A chalky white liquid is fed into the large bowel through the rectum. This makes the shape of the walls visible.

If you have a computer axial tomography (CAT) scan, also known as a CT scan, with oral contrast, diverticula can be seen.

Your doctor might want a closer look with an endoscope. This is a thin flexible tube with a tiny camera on the end. It's inserted via the rectum into the large bowel and sometimes further up. The technique is called colonoscopy. Both of these methods are regularly used in the search for other diseases. You may first learn that you have diverticula when you're seeing the doctor about something else.

Treatment and Prevention

The great majority of people with diverticulosis never experience mild bleeding, let alone fistulas or peritonitis.

If you have diverticula, your doctor may want to minimize their number to avert the possibility of diverticulitis. Medications don't usually help, but a high-roughage diet and sometimes bran or psyllium seed preparations such as Metamucil® or Prodiem® can help.

Esophageal diverticula are normally left in place, as they pose no danger.

Giant diverticula need to be removed surgically. They tend to cause serious obstruction and are likely to become infected and rupture. Giant diverticula are removed along with a small section of the colon (large bowel), and the two loose ends of the colon are sutured (joined) back together. This is called segmental resection of the colon.

Bleeding from a diverticulum may stop after the administration of medications such as vasopressin.* Sometimes, a doctor can stop the bleeding during a colonoscopy. If the bleeding does not stop, you may need a segmental resection, which is a surgical procedure to remove part of an organ (in this case, part of the intestines).

Many times, surgery can be performed laparoscopically, which is a less invasive surgery performed through very small incisions in the abdomen using a very specialized surgical instrument.

Mild diverticulitis can be treated at home with rest, a liquid diet, and antibiotics. You'll often feel better within a week, though it's still important to follow your doctor's instructions regarding diet for a few weeks after that. People with severe diverticulitis are treated in hospital. They're fed by intravenous drip to keep the gastrointestinal tract rested and empty, and given intravenous antibiotics.

About 20% of people with diverticulitis need surgery. Again, the standard procedure is segmental resection. This operation doesn't cause incontinence or any loss of bowel function. If peritonitis or other complications of the rupture of the bowel wall occur, surgery is needed to close the hole and/or drain the infection.

To prevent or slow the development of diverticula and diverticulitis, do the following to help promote a healthy bowel:

  • Increase the amount of fibre in your diet – eat high-fibre foods such as whole grains, fruits, and vegetables.
  • Drink lots of water throughout the day.
  • Exercise regularly.

*All medications have both common (generic) and brand names. The brand name is what a specific manufacturer calls the product (e.g., Tylenol®). The common name is the medical name for the medication (e.g., acetaminophen). A medication may have many brand names, but only one common name. This article lists medications by their common names. For information on a given medication, check our Drug Information database. For more information on brand names, speak with your doctor or pharmacist.