Ileostomy: Surgical creation of an external opening into the ILEUM for fecal diversion or drainage. This replacement for the RECTUM is usually created in patients with severe INFLAMMATORY BOWEL DISEASES. Loop (continent) or tube (incontinent) procedures are most often employed.Proctocolectomy, Restorative: A surgical procedure involving the excision of the COLON and RECTUM and the formation of an ILEOANAL RESERVOIR (pouch). In patients with intestinal diseases, such as ulcerative colitis, this procedure avoids the need for an OSTOMY by allowing for transanal defecation.Colostomy: The surgical construction of an opening between the colon and the surface of the body.Colectomy: Excision of a portion of the colon or of the whole colon. (Dorland, 28th ed)Colonic Pouches: Sacs or reservoirs created to function in place of the COLON and/or RECTUM in patients who have undergone restorative proctocolectomy (PROCTOCOLECTOMY, RESTORATIVE).Ileum: The distal and narrowest portion of the SMALL INTESTINE, between the JEJUNUM and the ILEOCECAL VALVE of the LARGE INTESTINE.Surgical Stapling: A technique of closing incisions and wounds, or of joining and connecting tissues, in which staples are used as sutures.Colitis, Ulcerative: Inflammation of the COLON that is predominantly confined to the MUCOSA. Its major symptoms include DIARRHEA, rectal BLEEDING, the passage of MUCUS, and ABDOMINAL PAIN.Anastomosis, Surgical: Surgical union or shunt between ducts, tubes or vessels. It may be end-to-end, end-to-side, side-to-end, or side-to-side.Rectum: The distal segment of the LARGE INTESTINE, between the SIGMOID COLON and the ANAL CANAL.Anal Canal: The terminal segment of the LARGE INTESTINE, beginning from the ampulla of the RECTUM and ending at the anus.Schilling Test: A diagnostic test in which vitamin B12 is tagged with radioactive cobalt, taken orally, and gastrointestinal absorption is determined via measurement of the amount of radioactivity in a 24-hour urine collection.Pouchitis: Acute INFLAMMATION in the INTESTINAL MUCOSA of the continent ileal reservoir (or pouch) in patients who have undergone ILEOSTOMY and restorative proctocolectomy (PROCTOCOLECTOMY, RESTORATIVE).Intestinal Obstruction: Any impairment, arrest, or reversal of the normal flow of INTESTINAL CONTENTS toward the ANAL CANAL.Defecation: The normal process of elimination of fecal material from the RECTUM.Postoperative Complications: Pathologic processes that affect patients after a surgical procedure. They may or may not be related to the disease for which the surgery was done, and they may or may not be direct results of the surgery.