Barium enema uses contrast material to help the provider evaluate the large intestine with an x-ray. As the name of the test implies, barium is placed in the bowel using an enema. The barium coats the lining of the intestine, creating a silhouette of the rectum, colon and a portion of the small intestine. This helps providers to see structures and irregularities on an x-ray. This test is not used as frequently as it once was.