The "air enema" in acute colitis.

The plain abdominal radiograph is an important investigation in acute colitis, but may fail to demonstrate the state of the colon owing to a lack of intracolonic gas. The extent of the colitis can be demonstrated by introducing air directly into the large bowel; the air also provides sufficient contrast to distinguish a granular from an ulcerated mucosa. The "air enema" may be used as an alternative to an unprepared barium enema. Its accuracy has been established by comparison with an unprepared barium enema in 10 patients with acute colitis.