Barium enema is a special x-ray of the large intestine, which includes the colon and rectum. Before x-rays are taken, a liquid called barium sulfate is placed in the rectum. The liquid is a type of contrast. Contrast highlights specific areas in the body, creating a clearer image. The barium eventually passes out of the body with the stools.

This test may be done in an office or a hospital radiology department. You lie on the x-ray table and a preliminary x-ray is taken. You will then be told to lie on your side. The health care provider will gently insert a well-lubricated tube (enema) into your rectum. The tube is connected to a bag that contains the barium. The barium flows into your colon.

A small balloon at the tip of the enema tube may be inflated to help keep the barium inside your colon. The health care provider monitors the flow of the barium on an x-ray fluoroscope screen, which is like a TV monitor.

There are two types of barium enemas:

• Single contrast barium enema uses barium to highlight your large intestine.
• Double contrast barium enema uses barium, but also delivers air into the colon to expand it. This allows for even better images.

You are asked to move into different positions and the table is slightly tipped to get different views. At certain times when the x-ray pictures are taken, you hold your breath and are still for a few seconds so the images won't be blurry.

The enema tube is removed after the pictures are taken. You will be given a bedpan or helped to the toilet, so you can empty your bowels and remove as much of the barium as possible. One or two x-rays may be taken after you use the bathroom.

You must completely empty your bowels before the exam. This may be done using an enema or laxatives combined with a clear liquid diet. Your health care provider will give you specific instructions. Thorough cleaning of the large intestine is necessary for accurate pictures.

When barium enters your colon, you may feel like you need to have a bowel movement. You may also have a feeling of fullness, moderate to severe cramping, and general discomfort. Try to take long, deep breaths during the procedure. This may help you relax.

The barium enema is used to detect colon cancer. It may also be used to diagnose and evaluate the extent of inflammatory bowel disease.

Barium should fill the colon evenly, showing normal bowel shape and position and no blockages.

Abnormal test results may be a sign of:

• Acute appendicitis
• Cancer
• Colorectal polyps
• Diverticulitis
• Irritable colon
• Twisted loop of the bowel
• Ulcerative colitis

Additional conditions under which the test may be performed:

• Crohn's disease
• Hirschsprung's disease
• Intestinal obstruction
• Intussusception
• Ulcerative colitis

There is low radiation exposure. X-rays are monitored and regulated to provide the smallest amount of radiation exposure needed to produce the image. Most experts feel that the risk is low compared with the benefits. Pregnant women and children are more sensitive to the risks of the x-ray.

A more serious risk is a perforated colon, which is very rare.

Colonoscopy is another way to diagnose and monitor diseases in the colon.