[Safety and efficacy of laparoscopic distal rectal transection by transanterior obturator nerve gateway]

Objective: To evaluate the safety and efficacy of distal rectal transection by using transanterior obturator nerve gateway (TANG) in laparoscopic radical resection for lower rectal cancers. Methods: A descriptive case series study was performed. Inclusion criteria: (1) patients with primary rectal adenocarcinoma, with the distance of 3-5 cm from tumor to anal verge, with normal anal function before surgery and a desire to preserve anus; (2) laparoscopic radical resection of rectal cancer was performed and the distal rectum was transected using TANG approach. Exclusion criteria: (1) patients with distant metastasis or receiving palliative surgery; (2) the distal rectum was transected using non-TANG approach; (3) patients receiving combined multiple organs resection; (4) patients complicated with other tumors requiring additional treatment during the study. Clinicopathological data of 50 patients with low rectal cancer undergoing laparoscopic resection using TANG approach between January 2019 and December 2020 in Peking University First Hospital were retrospectively collected. Perioperative conditions, length of specific pelvic lines, additional angle and postoperative short-term outcomes were observed and described. Additional angle was defined as the angle between the simulated stapling line with the traditional approach and the real stapling line with the TANG approach. Data following normal distribution were presented as Mean±SD, or M [quartile range (Q(R))] otherwise. Results: All the patients successfully completed laparoscopic surgery without transferring to open or transanal surgery. The median operative time was 193 (80) min and blood loss was 50 (58) ml. All tumors received R0 resection with the distance from the tumor to distal resection margin of 1.7 (0.4) cm and the anastomotic height of 2.0 (0.1) cm. Rectal transection was completed by one cartridge in 52.0% of the cases (26/50) and two cartridges in 48.0% (24/50). Length of the stapling line was 6.6 (1.5) cm. The time to construct the gateway was 8.0 (6.0) min. The vessel damage occurred in 4.0% of the cases (2/50) and none of the cases encountered obturator nerve damage. Inlets of the pelvis in TANG and traditional approach were (9.9±1.3) cm vs. (7.2±1.1) cm (t=24.781, P<0.001). Additional angle of TANG was (15±2) °. The transecting positions on the midline and right edge of the rectum specimen by TANG were 0.6 (0.2) cm and 1.0 (0.2) cm lower than those by the traditional approach. One case (2.0%) died of pulmonary infection on the 17th day after surgery, 2 cases (4.0%) received re-operation and 14 cases (28.0%) had postoperative complications, including anastomotic leakage (7/50, 14.0%), urinary retention (6/50, 12.0%), pelvic infection (2/50, 4.0%) and ileus (2/50, 4.0%). The median postoperative hospital stay was 12 (6) days. Conclusions: Laparoscopic distal rectal transection by using TANG approach is safe and effective in the treatment of low rectal cancer. As an alternative rectal transecting method, TANG has advantages especially for the obese and those with a contracted pelvis and ultralow rectal cancers.