Patients undergoing bowel surgery may not be able to empty their bowels the natural way. In some cases this is a temporary state of affairs, in other cases it may be a permanent change. In either case a 'stoma' will need to be used.
A stoma (which literally means an 'opening') is a pouch or bag that is fitted to a small hole in the skin of the abdomen where a section of the bowel has been attached. The contents of the bowel empty into the stoma instead of taking the natural path to the anus. Where the stoma is attached to a section of the large bowel, it is called a 'colostomy' and where it is attached to a section of the small bowel it is called an 'ileostomy'.
In some cases where the bowel simply needs some time to recover from the initial surgery, the two sections of the bowel can be joined together again in another procedure weeks or months later, and normal bowel emptying via the anus can resume. In other cases, especially where either inflammatory bowel disease or cancer has affected the rectum or anus, the stoma may need to be permanent.