Transanal Total Mesorectal Excision: Pneumodissection of Retroperitoneal Structures Eases Laparoscopic Rectal Resection.

INTRODUCTION: Laparoscopic total mesorectal excision is effective and safe but often technically challenging because of inadequate exposure. Transanal total mesorectal excision was introduced to mitigate this limitation and improve the quality of mesorectal dissection in even the most challenging cases. Currently, the technique for transanal total mesorectal excision dissection is not standardized.

TECHNIQUE: The sequential approach to transanal total mesorectal excision mirrors the principles of the transanal abdominal transanal procedure. It begins with the transanal step, followed by the laparoscopic step, and then the transanal total mesorectal excision. The perirectal space is entered via a full-thickness dissection of the anterior rectal wall. Carbon dioxide is left flowing, widening the embryonic planes between the mesorectal and pelvic fascias, then moving upward through the retroperitoneal space. The surgeon switches to the abdominal field and begins laparoscopic dissection, consisting of inferior mesenteric artery dissection and division, inferior mesenteric vein dissection and division, and possible splenic flexure dissection. Pneumodissection facilitates this procedure by distancing the inferior mesenteric artery from the hypogastric nerves and opening the embryonic fusion plane between the Toldt and Gerota fascias to allow faster division of the left colon lateral attachments. The operation continues with a switch to the perineal field and mesorectal excision.

RESULTS: A total of 102 patients underwent transanal total mesorectal excision as described. Mean operative time was 185.0 + 87.5 minutes (range, 60-480 min), and there was no conversion to open surgery. Postoperative morbidity was 33.3%. Mortality rate at 30 days was 1.96% (2 cases). Quality of mesorectal excision according to Quirke was assessed in all of the specimens and found to be complete in 99 cases (97.1%) and nearly complete in 2.9% of cases.

CONCLUSIONS: Transanal total mesorectal excision may benefit from pneumodissection, expedites the laparoscopic step, and the sequential approach facilitates the visualization of the correct dissection planes. The safety and cost-effectiveness of the procedure still warrant consideration. See Video at https://links.lww.com/DCR/A418.