A stoma is an opening connecting an internal organ to the surface of the body that is formed by surgery. The most common types of stoma in intestinal surgery are an "ileostomy" (connecting the small intestine to the skin) and a "colostomy" (connecting the large intestine to the skin).
A stoma may be temporary or permanent. In colorectal surgery, a temporary ileostomy is most often created at surgery to divert stools away, so that the operation site below is allowed to heal without irritation by stools passing through. This can be reversed with a subsequent small operation, with minimal or no loss of intestinal function.
A permanent stoma may be required when disease, or its treatment, leads to loss of normal intestinal function, or when the muscles that control the anus do not work properly or require removal. The most common conditions where a permanent stoma is required are low rectal cancers and inflammatory bowel disease.