A barium enema is a procedure that allows your doctor to assess the lining of your rectum and colon using x-rays. To have a barium enema, you will first undergo a bowel prep similar to the one used for colonoscopy. On the day of your examination, a tube is gently placed into your rectum, and barium liquid is slowly pumped into your colon. The barium liquid coats your colon and rectum so that it shows up clearly on the x-ray. This is a good way to look for disease and any narrowed areas or large tumors, but it may miss small polyps, cancers, or inflammation. If a problem is found, a colonoscopy may still be required. A perforation or a tear in the lining of the intestine occurs in about one out of every 25,000 barium enemas.