50 - Abdominoperineal resection

Summary

Abdominoperineal resection (Miles' operation) with excision of the rectum, anus, and sphincter muscles and creation of a permanent end colostomy is performed to remove malignant neoplasms of the mid or lower rectum or anus – adenocarcinoma, carcinoid, lymphoma, squamous cell carcinoma remaining after chemotherapy, cloacogenic carcinoma, basal cell carcinoma, and malignant melanoma – or extensive Crohn's disease with fistulas of the same areas. The operation is conducted with a transabdominal laparoscopic approach or through a low midline laparotomy incision and a circumferential perianal incision and is essentially a posterior exenteration of the pelvis. Included in the excision are the rectosigmoid colon, the rectum, the pelvic mesocolon, the lymph nodes associated with the three sets of hemorrhoidal vessels, the levator muscles out to the ischial tuberosities, the anus, and the perianal skin. As an alternate approach, many surgeons use low anterior transabdominal resection with an anastomosis in patients with adenocarcinoma of the upper or mid-rectum because it produces an essentially equivalent survival and precludes the need for a colostomy. The surgeon must be able to excise a 2 cm margin of normal bowel beyond the rectal tumor and to have enough rectum left at or above the levator muscles to allow the performance of a stapled or handsewn anastomosis.

A related approach is excision of the rectum alone (without the mesocolon or lymph nodes) and preservation of a seromuscular short rectal cuff to maintain anal continence through the creation of an ileal pouch–anal anastomosis in patients with severe chronic ulcerative colitis, familial polyposis, or Gardner's syndrome, but not in those with Crohn's disease.