During a barium enema, a thick solution of a barium contrast is inserted into the rectum while a radiologist watches the progress of the contrast on a TV screen as it moves through the entire colon. Individual “spot” x-rays are taken along the way.
For screening, a double-contrast procedure is more accurate. After the first views with barium are taken, the barium contrast is drained through the anus leaving a thin layer along the walls of the rectum and colon. Air is then blown gently into the colon and additional x-rays made.
You’ll probably feel pressure and the need to have a bowel movement during the procedure. A small balloon is inflated to keep barium inside your rectum so you don’t need to worry about an accident. Inflated air can be uncomfortable, and you may have some cramping.
The rectum and colon need to be clear of stool for good images, so clear liquids are usually recommended the day before the exam, along with laxatives, suppositories, or enemas. Your doctor will provide instructions for you to follow before and after the exam.
Barium enema is rarely used for screening today, but is appropriate for some patients. It does visualize the entire colon, but takes skill to administer and interpret accurately.
You can watch a video of a barium enema on MayoClinic.Com.
If polyps or possible cancer are identified during barium enema, colonoscopy is necessary to remove polyps and biopsy suspicious lesions.