Abdominoperineal Resection
Principles of Preoperative Evaluation
The patient is screened with a full colonoscopy. Digital rectal examination and proctoscopy are performed to confirm tumor location and to assess feasibility of a sphincter-sparing approach (Fig. 25-1, A). Digital vaginal examination and vaginoscopy are performed with the proctoscope to assess for local invasion. CT scanning of the chest, abdomen, and pelvis is done to survey for metastatic disease. Endorectal ultrasound is used for staging to assess the need for preoperative chemoradiation (Fig. 25-1, B).
Anatomic Approach to Left Colon Mobilization
The mobilization is extended to the root of the mesentery, and the inferior mesenteric artery is identified at its takeoff from the aorta (Fig. 25-2, A). Branches of the sympathetic nerves, which lie deep to the IMA, are protected by keeping close to the fascia of the mesocolon as it wraps around the IMA, if necessary sweeping nerve branches dorsally and away from the vessel (Fig. 25-2, B). The IMA is isolated, clamped, and ligated. The left colic artery and the inferior mesenteric vein are divided and ligated at the level of the IMA (Fig. 25-2, C)