This operation involves the removal of the sigmoid colon and a variable portion of the upper rectum and left colon. The grey area of the diagram above. The exact margins of resection are at the discretion of the surgeon and are appropriate to each patient and condition treated.

The operation is carried out for a variety of disorders but most commonly for bowel cancer and diverticular disease. The operation may be performed laparoscopically but for many reasons an open procedure is usually necessary particularly if an emergency. The bowel is freed from its attachments within the abdominal cavity and its blood supply is divided.

The bowel is then cut, the diseased segment is removed and the colon brought out through the abdominal wall and stitched to the skin as a colostomy. The rectum is closed off with stitches or staples and returned to the pelvis. The procedure is usually reversible by surgery at a later date.