open intersphincteric rectal resection, with transanal colon pull-through and pouch formation

Opening of the abdominal cavity through a median laparotomy. It is very important to ensure that the skin incision is actually carried down to the symphysis, as otherwise access to the pelvis is significantly impeded. Afterwards, a covering, in this case a foil, is inserted and the abdominal walls are held aside by means of a retractor. Next, the intraoperative assessment of findings takes place (not shown).

The mobilization of the left flexure occurs alternately from aboral by dissecting the descending colon in an avascular layer in front of the left kidney and from oral by detaching the greater omentum from the colon up to about the middle of the transverse colon with opening of the omental bursa. Finally, the connections to the spleen and pancreas are released.

The inferior mesenteric vein, the ligament of Treitz, and the arterial supply are clearly identified. Then, the exposure is first performed and then the transection of the inferior mesenteric vein between Overholt clamps at the lower border of the pancreas.

The inferior mesenteric artery is divided while sparing the superior hypogastric plexus approximately 1–2cm distal to its origin from the aorta, but proximal to the takeoff of the left colic artery, including the central lymph nodes. The central vascular stump is secured with a transfixing ligature.

Tip: Central ligation of the inferior mesenteric artery is not oncologically mandatory in rectal carcinoma. However, compared to selective ligation of the superior rectal artery while preserving the left colic artery, a tension-free anastomosis can be created more easily, which is why this approach is usually favored despite the potential disadvantages (poorer perfusion, damage to the preaortic nerves).

Note: A primary vessel division is a priori oncologically sensible, but an advantage has not been proven by studies.

After head-down positioning, preparation is first made from the right lateral side into the lesser pelvis by transecting the pelvic floor peritoneum at the peritoneal reflection fold. Then, entry is made into the mesorectal plane from the dorsal side with careful preservation of the nerves in the lesser pelvis. Finally, entry into the dorsal plane is made in a similar manner also on the left side, starting with an incision of the peritoneum at the lateral reflection.

Note: Already here, meticulous attention must be paid to the preservation of the mesorectum.

The next step is the complete detachment of the mesorectum from the presacral fascia and then further distally to the tubular muscle sheath of the anorectal junction at the level of the puborectalis sling or the muscular pelvic floor, while both ureters and the autonomic nerve supply of the pelvis must be identified and spared, ligamentous structures between the coccyx and rectum are severed

Note: The mesorectal fascia is an enveloping fascia that surrounds the perirectal adipose tissue. The basis of total mesorectal excision (TME) is the preservation of this fascia to minimize the risk of tumor cell dissemination.

After incision of the ventral peritoneal reflection between the bladder or uterus and the rectum, the Denonvilliers' fascia is entered. In this layer, the preparation proceeds to supra- or intersphincteric. Care must be taken to spare the nerve and venous plexus covering the seminal vesicles in men. Anterolaterally at the pelvic floor, the inferior hypogastric plexus must be spared. Here, the circular continuity of the boundary lamellae is interrupted and the rectal fascia propria is fixed to the pelvic wall. In this attachment to the lateral pelvic wall, fine nerves and the variably positioned middle rectal artery (so-called T-junction) run. Too lateral detachment of the T-junction damages the inferior hypogastric plexus and must be avoided.

Now the rectal palpation is performed to check the sufficient depth of the preparation and the relation to the tumor. Also, by visualizing the puborectalis sling, the sufficient preparation depth can be confirmed.

The hooks are placed perianally at the transition to the shiny skin of the anal canal and the anal funnel is thereby retracted. For hemostasis, the intersphincteric area above the dentate line is infiltrated with epinephrine solution (e.g., 1:100,000).