Lower gastrointestinal (GI) barium tests are used to diagnose conditions that affect a person’s colon and rectum. The procedures are sometimes called barium enemas (enemas involve fluid put into the rectum) because a thick liquid called barium is used to highlight the region on x-rays.

Lower GI barium tests may be administered in a physician’s office or the radiology department of a hospital.  Prior to the test, the lower GI tract must be completely emptied of stool and gas. This can be accomplished in a number of ways (e.g., special diet, use of laxatives and/or enemas).

During these tests, a barium bag is connected to a tube and the barium contrast agent is slowly administered through the tube into the colon. Enough barium is administered to fill up the patient’s colon. Images are then taken of the colon.

There are two major types of lower GI barium tests:

• Single-contrast barium enema. Involves an enema using a barium compound that is administered before fluoroscopy (examination with a fluoroscope, an x-ray machine that combines an x-ray source with a fluorescent screen) or conventional x-rays of the large intestine.
  
  
• Double-contrast barium enema. Also called an air-contrast barium enema, it involves a standard barium enema followed by air insufflation into the rectum and colon. Polyps and small cancers can be detected more readily with this method. The U.S. Centers for Disease Control and Prevention (CDC) recommends that people ages 50 and older have a double-contrast barium enema test every five years as part of their colorectal cancer screening routine.
  
  

  

The images captured during a lower GI barium test are read and interpreted by a radiologist, who offers an analysis to the patient’s physician. Typically, results are ready within a week of the procedure. If abnormalities are discovered, follow-up procedure or treatments may be scheduled.