What Is Diverticulitis?

Diverticular disease is a common condition that is characterized by the presence of pouches in the wall of the colon, called diverticula. In most cases, diverticula do not cause any symptoms, but sometimes they can become inflamed and/or infected, which causes a condition called diverticulitis.

While about half of people over the age of 60 have diverticula in their colon, only about 10% to 25% of those individuals go on to develop diverticulitis.

The Large Intestine

Diverticula generally occur in the colon, which is part of the large intestine. Most of the time, diverticula develop in the sigmoid colon, which is the last section of the large intestine that is connected to the rectum. The sigmoid colon is located on the left side of the abdomen, which is why diverticulitis is often associated with abdominal pain on that side.

Diverticula can occur in other parts of the large intestine too, but this is less common. 

Diverticulitis Symptoms

The most common symptom of diverticulitis is abdominal pain, which tends to be constant and may also last for several days. In some cases, the pain can be severe. Rectal bleeding can occur, but it is not common in diverticulitis. Other symptoms can include:

• abdominal pain and tenderness (usually left-sided, may be severe)
• chills
• constipation
• cramping
• bloating
• diarrhea (occasionally)
• gas
• fever
• lack of appetite
• nausea
• vomiting
• rectal bleeding (not common)

Causes

It's not known why some people with diverticular disease develop diverticulitis. There are theories being researched, but researchers currently have no definitive answers about the cause(s) of diverticulitis. It was thought that eating certain foods such as seeds, nuts, or corn, could trigger diverticulitis in people who had diverticular disease, but this is no longer believed to be the case.

There is some recent evidence from studies done in men that eating more red meat may be associated with a higher risk of developing diverticulitis.

Another theory is that there is an association with a virus called cytomegalovirus (CMV). CMV is common and may be passed from person to person through bodily fluids. When CMV is first contracted it might cause symptoms similar to the flu (fever, sore throat, fatigue, swollen lymph nodes) but then it may go into an inactive stage. The virus may remain dormant in the body. However, in some cases the virus can be reactivated. It’s thought that the reactivation of CMV might have a connection to diverticulitis.  

Other potential factors that may contribute to the development of diverticulitis include:

• buildup of unhealthy bacteria in a diverticula
• disruption in the level of healthy bacteria in the colon  
• overweight
• sedentary lifestyle
• smoking
• nonsteroidal anti-inflammatory drugs (NSAIDs)
• steroid medications

Diagnosis

Diverticulitis is diagnosed with an abdominal computed tomography (CT) scan.

A CT scan is a type of X-ray that is done with the use of contrast dye. Contrast dye is drunk as well as given through an IV. This is to ensure that the structure of the colon is thoroughly visualized and a diagnosis of diverticulitis can be made.

In some cases, additional testing might be used if it’s suspected that there are other conditions or complications associated with the diverticulitis. These will be highly individualized based on how the patient is doing as well as physician preference.

Diverticulitis Doctor Discussion Guide

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Treatment

For patients who have uncomplicated diverticulitis, which means there are no associated problems such as an abscess or a fistula, treatment is usually done at home. A liquid diet and rest are usually prescribed along with antibiotics.

For more complicated diverticulitis, where there are severe symptoms or other conditions, treatment in the hospital might be needed. Hospital treatment may include fasting (often called nothing by mouth or NPO), IV fluids, and antibiotics. Most patients improve quickly.

Surgery is usually only done when there another serious problem occurs, such as a perforation in the colon.

A Word From Verywell

Most older people have diverticula that don’t cause any symptoms and it’s only in a small amount of cases that diverticulitis develops. It’s still not clear why inflammation and/or infection of the diverticula happens, but it’s no longer thought to be the result of eating fibrous foods and might instead be caused by a number of factors.

Most cases of diverticulitis are not complicated and can be treated at home with rest and fluids, although sometimes antibiotics might also be prescribed. For people who are very ill, treatment will be needed in the hospital with IV fluids and antibiotics. Other treatments might also be needed, but this is going to vary on the health of the patient and the preference of the healthcare team.