Abdominoperineal resection (APR, Miles' operation), with excision of the rectum, anus, and sphincter muscles and the creation of a permanent end colostomy, is performed to remove malignant neoplasms of the distal one-third of the rectum or the anus. The most common indication for resection is adenocarcinoma of the rectum or anus that cannot be removed with adequate margins at the time of primary resection, or recurrent disease. Less common indications for APR include residual squamous cell carcinoma of the anus after chemo-radiation treatment, carcinoid, cloacogenic carcinoma, basal cell carcinoma, and malignant melanoma. Abdominoperineal resection is most commonly performed for non-malignant disease in the setting of medically refractory Crohn's disease with severe perianal fistulae.

The operation is conducted with a transabdominal laparoscopic approach or through a low midline laparotomy incision and a circumferential perianal incision. 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. The resection of the levator and anal complex necessitates an end-descending colostomy. In instances when the surgeon is able to excise a 2 cm margin of normal bowel beyond the rectal tumor, a Miles' procedure with a permanent colostomy can be avoided by performing a low hand-sewn or stapled coloanal anastomosis accompanied by a temporary diverting ostomy while the anastomosis heals.