The surgical formation of an opening through the abdominal wall into the ileum (the lower part of the small intestine). The operation is performed whenever the colon has to be removed; the opening then acts as an artificial anus through which the contents of the small intestine are discharged instead of passing through the colon to the natural anus.

The opening does not have muscles like the opening of the natural anus, so if one has an ileostomy one will have to wear a bag continually to collect the fecal matter. This sounds unwieldy, but in fact an ileostomy is perfectly compatible with normal life. The colon (large intestine) absorbs water from the intestinal contents. But the waste products discharged through an ileostomy have not passed along the colon; thus they are watery, especially for a time just after the colon has been removed. Later one’s body will adapt and the fecal matter will gradually become more formed although never completely solid.

One may have to make some minor changes in diet to alter the consistency of the stools or to reduce odor. One will learn how to look after one’s ileostomy at the hospital where the operation is performed. Additional help may be obtained from the United Ostomy Association or its chapters, which exist in all fifty states.