Intersphincteric resection, open, with transanal colon pull-through and transverse coloplasty pouch

Longitudinal laparotomy.

Free the left colon up to the middle of the transverse colon with release of the splenic flexure. Identify and dissect the inferior mesenteric vein, ligament of Treitz and the arterial blood supply.

High ligation and suture ligation of the inferior mesenteric vein at the inferior aspect of the pancreas.

After suture ligation of the inferior mesenteric artery close to its origin, divide the artery while sparing the superior hypogastric plexus.

After instituting Trendelenburg position, open the peritoneum at the base of the mesosigmoid and mesorectum on both sides from anteriorly to the promontory down to the pouch of Douglas, and then open the "holy plain" posterior to the mesorectum, respecting the layers and the hypogastric nerves.
Perform this dissection akin to total mesenteric excision.