Introduction of fluid into the RECTUM via the ANUS. Enemas may be given to clear the intestine of faeces prior to intestinal surgery or to relieve severe constipation. They may also be used to give barium for diagnostic X-rays as well as drugs such as CORTICOSTEROIDS, used to treat ULCERATIVE COLITIS. The patient is placed on his or her side with a support under the hips. A CATHETER with a lubricated end is inserted into the rectum and warmed enema fluid gently injected. Disposable enemas and miniature enemas, which can be self-administered, are widely used; they contain pre-prepared solution.