The operation by which an artificial opening is made into the ILEUM and brought through the abdominal wall to create an artificial opening or STOMA. It is most often performed as part of the operation for cancer of the RECTUM, in which the rectum has usually to be removed. An ileostomy is then performed which acts as an artificial anus, to which a bag is attached to collect the waste matter. Distressing though this may be at first, the vast majority of people with an ileostomy learn to lead a fully active and normal life.