Diverticulosis and Diverticulitis: What You Should Know

Medically Reviewed

As we age, most of us develop small pouches (diverticula), usually the size of a large pea, that bulge outward through weak points in the wall of the large intestine, a condition termed diverticulosis. It occurs in about half of Americans between the ages of 60 and 80, and in 70 percent of people 80 and up.

Diverticula, which by themselves don’t cause a problem, can become inflamed or infected, which is called diverticulitis. The incidence of this is less common than previously thought, occurring in only 1 to 4 percent of patients with diverticula.

Although diverticulosis can occur anywhere along the length of the colon, the pouches typically develop in the sigmoid colon, the last portion before the rectum, where colonic contractions and pressures are the highest. The number of diverticula can range from one (called a diverticulum) to dozens.

A low-fiber diet had been considered the major culprit in diverticulosis. But recent research suggests that a lack of fiber is not to blame.

No one knows for sure what causes diverticulosis, but genetics appear to play a role because the condition is more common among family members.

Symptoms and complications

Most people with diverticulosis have no discomfort or symptoms. Some patients experience mild abdominal pain, bloating, and irregular bowel habits.

The pain typically occurs in the lower abdomen, most often on the left side. This area of the abdomen may feel full and occasionally tender when touched. More often a patient will experience cramping.

The symptoms also are commonly seen in people who have irritable bowel syndrome (IBS), and the formation of diverticula may share a common cause with IBS.

With diverticulitis, on the other hand, the pain can be severe and fluctuate in intensity. It may occur with more cramping, nausea, vomiting, chills, fever, a change in bowel habits, painful or difficult urination, and increased frequency of urination.

The type and severity of the symptoms usually depends upon the extent of the infection and the potential involvement of surrounding organs.

People with diverticulosis may experience painless bleeding from the rectum, which occurs when a small blood vessel adjacent to the diverticulum ruptures.

This is the most common cause of significant lower gastrointestinal bleeding in elderly people. It is more likely to occur when taking aspirin or other nonsteroidal anti-inflammatory drugs. The bleeding usually stops on its own.

If bleeding persists or recurs, a therapeutic endoscopy may be needed or possibly surgery to remove the portion of the colon containing the bleeding diverticulum.

A radiology specialist can perform a procedure that may be able to close the blood vessel that is causing the hemorrhage.

Diagnosis of diverticulosis and diverticulitis

Diverticulosis is often discovered by accident during an exam, such as a CT scan, barium enema, or sigmoidoscopy, generally performed for another reason or for another ailment.

If you have symptoms suggestive of some abdominal condition, your doctor may order one or more of those tests to determine if diverticulosis or diverticulits is causing the problem.

In certain clinical situations, your doctor may also recommend a colonoscopy to check whether cancer is causing the symptoms.

Treatment of diverticulosis and diverticulitis

Though the link between fiber intake and the development of diverticulosis is still uncertain, a high fiber diet is advised once diverticula are noticed because it may prevent diverticulitis from occurring.

Fiber supplements containing psyllium may also be helpful, along with exercise, not smoking, and weight control. Nuts, corn, seeds, and popcorn do not need to be avoided.

A milder case of diverticulitis may improve on its own, and most cases can be treated at home with rest, a liquid diet, and oral antibiotics. People who have severe diverticulitis need to be hospitalized and treated with intravenous antibiotics, but in most cases they will not require surgery.

An abscess (a collection of pus surrounded by inflamed tissue) may form in the abdominal cavity adjacent to the colon as a complication of diverticulitis.

The abscess can often be managed with antibiotics but may also need to be removed by inserting a needle through the skin and draining the infected fluid through a catheter. Surgical treatment is necessary in some people with a resistant infection.

Rarely, the infection may leak out of an abscess and spread into the abdominal cavity, causing a condition called peritonitis. In such cases, surgery is required immediately to clean the abdominal cavity and remove the damaged region of the colon.

A fistula (an abnormal connection between two organs) can form when inflammation from diverticulitis erodes the colon wall, creating a passage between the colon and an adjacent organ such as the bladder, small intestine, vagina, or skin.

The most common type of fistula connects the colon and the bladder. This abnormality, which occurs more often in men than in women, can lead to severe, persistent urinary tract infections. Surgery to remove the fistula and the affected part of the colon is needed to correct the problem.

For recurrent diverticulitis, the use of a class of anti-inflammatory drugs known as mesalamines may help control and avoid further episodes. More research is needed to see if mesalamines combined with probiotics may also be useful.

If medical therapy and lifestyle changes don’t prevent recurring episodes, surgical removal of the involved portion of the colon might be necessary. Repeated episodes of diverticulitis generally occur in the same region within the colon.