Transanal endoscopic microsurgery-based transanal access for colorectal surgery: experience on human cadavers

Transanal endoscopic microsurgery (TEM) was described in 1983 for local excision of rectal tumors. In the context of natural orifice translumenal endoscopic surgery, we have modified the original TEM system and developed a new set of instruments. These are more curved and, in addition, steerable. After extensive studies in an ex-vivo model, we developed a novel technique for transanal rectosigmoid resection and colorectal anastomosis. The technique comprises closure of the rectal lumen by purse-string suture, transection of the rectal wall distal to the closure, circumferential mobilization of rectum and mesorectal tissue in the anatomical plane from below upward, control of the inferior mesenteric vessel, removal of mobilized colorectum through the anus, and, finally, the colorectal anastomosis by either stapled or hand-sutured technique. This procedure was performed on three alcohol-glycerol preserved well-built human cadavers (M:F=2:1). The average operating time was 190 minutes. The average length of the resected specimen was 23 cm. There was no fecal contamination or injury to the resected specimen. Postprocedure laparotomy revealed adequate mesorectal resection and no inadvertent injury to other viscera. During dissection in the pelvis, as the resected rectum was pushed upward, an unobstructed "empty pelvis" situation was developed in the operating site, thus facilitating the mesorectal resection. Transanal access for colorectal surgery seems feasible. It provides a precise definition of the distal safety margin, good view of the pelvis for meticulous mesorectal resection, and reduces the abdominal wall trauma. These may enhance the outcome of colorectal resection. However, further clinical studies can only substantiate these findings.