A barium enema, or lower gastrointestinal (GI) examination, is an X-ray examination of the large intestine (colon and rectum). The test is used to help find problems that affect the large intestine.

To make the intestine visible on an X-ray picture, the colon is filled with a white barium contrast material. The contrast material is put through a tube placed in the anus. The barium blocks X-rays, so the barium-filled colon shows up clearly on the X-ray picture.

A barium enema may be done to check for the cause of rectal bleeding or blood in the stool. The test may help find diseases such as inflammatory bowel disease and diverticulosis. Other problems can also be found during a barium enema, such as a large polyp or colon cancer.