Barium enema: Viewing the colon for abnormalities

By Mayoclinic.com

Though sometimes unpleasant, a barium enema — colon X-ray — can help detect changes and abnormalities in your colon.

The barium enema — a distinct kind of colon X-ray — is used to detect changes or abnormalities in your colon. During the exam, liquid barium — and in some cases air — is instilled into your rectum and colon. This is done to improve the images of your colon made by the X-ray machine.

This test allows your doctor to examine your colon for:

• Ulcers

• Narrowed areas (strictures)

• Growths of the lining (polyps)

• Small pouches in the wall (diverticula)

• Cancer

• Other abnormalities

How do you prepare?

Before the exam, your colon must be completely emptied of all stool. You may be told to take laxatives and to have an enema before the exam.

Your doctor provides specific instructions about what to eat or drink before the test. You may be put on a clear liquid diet for a day or two before the barium enema. Clear liquids include:

• Plain water

• Tea and coffee without milk or cream

• Any juice without pulp (no orange juice or tomato juice)

• Broth

• Carbonated beverages

How is it done?

There are two types of barium enemas — single-column and air-contrast (double-contrast). The double-contrast barium enema is the type usually recommended for colorectal cancer screening.

Single-column barium enema
During this test, you lie on your side on the table of an X-ray machine. A lubricated enema tube is inserted into your rectum. The radiologist connects a barium bag to the tube to deliver liquid barium into your colon.

Barium sulfate is a soft, metallic alkaline chemical. The barium temporarily coats the lining of your colon. This provides a clear silhouette of the shape and condition of your colon to show up on X-rays.

As your colon fills with barium, you may feel the urge to have a bowel movement. The tube that's used to deliver the barium has a small balloon near its tip. When positioned at the entrance of your rectum, this balloon is inflated to keep the barium from spilling out your rectum. Taking long, deep breaths through your mouth may help you relax.

You may be asked to turn and maintain various positions during the exam. This helps ensure that your entire colon is coated with barium and allows the radiologist to view the colon from various angles. The radiologist may press firmly on your abdomen and pelvis, manipulating your colon for better viewing. You also may be asked to hold your breath at times.

The radiologist can view your colon's shape on a television monitor attached to the X-ray machine. He or she will also take a number of X-ray images of your colon from various angles.

Air-contrast (double-contrast) barium enema
This procedure is similar to a single-column barium enema. The main difference is that your colon is inflated with air in addition to the barium to expand it and improve the quality of the images. The air-contrast method increases the radiologist's ability to see small abnormalities, such as polyps.

A barium enema exam can last from 20 to 30 minutes up to 45 minutes. Both types of barium enemas can cause some minor abdominal cramping. Cramping usually ends soon after the test is completed.

After the exam, the radiologist removes the enema tip to allow you to expel most of the barium from your colon.

You'll probably produce white, gray or pink stools during the next few days as the remaining barium is expelled from your colon. You may be given a cleansing enema or be instructed to take a laxative to flush out the remaining barium. Because barium can cause constipation, you'll be advised to drink extra liquids during the next few days.

• constipation

Check with your doctor if your stool isn't of typical color within two to three days. Also contact your doctor promptly if you're unable to have a bowel movement or to pass gas more than two days after the exam. This may indicate that some of the barium remains in your colon.

Results

The barium enema test is considered negative if the radiologist didn't find any abnormalities in your colon.

If your barium enema is positive, you may have an abnormality in your colon. Depending on the findings, you may be scheduled for additional testing, such as a colonoscopy, so that any abnormalities can be examined more thoroughly, and — if necessary — biopsied or removed.

Ask your doctor whether the exam was of good quality. If your colon wasn't completely empty of stool before the exam, parts of the colon may not have been well visualized on the X-ray. In this case, there may be abnormalities that weren't detected. Your doctor may recommend that you have another barium enema in one year or even sooner. Some health care providers also recommend a flexible sigmoidoscopy in addition to a barium enema to provide an even better view of the rectum and sigmoid colon.

Here are the pros and cons of barium enema:

Pros

• No sedation is needed.

• When combined with flexible sigmoidoscopy, it screens the entire colon.

• Complications, such as perforation of the colorectal wall, are slight.

• It's less costly than colonoscopy, costing about $250 to $500. Additional fees may apply.

• If you're 50 or older and have Medicare benefits, coverage includes a barium enema every four years for colorectal cancer screening as an alternative to colonoscopy.

• If you're at high risk of colorectal cancer, Medicare covers a barium enema every two years as an alternative to colonoscopy. However, colonoscopy is usually preferred.

Cons

• The test may miss small polyps or sometimes even small cancers.

• Biopsy and polyp removal cannot be done during testing, meaning you may need to follow up with a colonoscopy.

• Preparing for the procedure (emptying the colon) and the procedure itself can be unpleasant.