TransAnal Minimally Invasive Surgery (TAMIS) with SILS™ Port versus Transanal Endoscopic Microsurgery (TEM): a comparative experimental study

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TransAnal Minimally Invasive Surgery (TAMIS) has been proposed as an alternative to Transanal Endoscopic Microsurgery (TEM) for resection of benign polyps and early cancers of rectum. Since clinical application has begun in the absence of any experimental validation, we assessed its feasibility and efficacy ex vivo in a pilot study. In a dedicated trainer box for transanal procedures, 10 surgeons with no experience in transanal surgery were asked to perform a dissection/suture task using both TAMIS and TEM in randomly allocated order. Surgeons were asked to dissect two identically drawn lesions of ~3cm in larger diameter. Precision of dissection was assessed using a quantitative photographic method, while the time needed for dissection and suturing was considered a measure of quantitative evaluation. Each participant expressed a subjective opinion regarding difficulty with dissection, difficulty with suturing, vision quality, and conflict between instruments on a scale from 1 to 5. No difference was observed between the two techniques regarding the accuracy of dissection as the margin was interrupted along 4.1% of the circumference in the TEM group compared with 2.48% in the SILS group (P=0.271). Dissection and suturing were significantly quicker in the TEM group [04:30 vs. 06:35min (P=0.049) and 14:34 versus 19:18min (P=0.003)]. In three cases in the SILS group, completing the suture was not considered possible, and the procedures were terminated by TEM. Subjective evaluation revealed a better appreciation of TEM in all proposed comparisons: dissection (2.6 vs. 3.5, P=0.004), suturing difficulty (3.1 vs. 4.6, P<0.001), quality of vision (2.3 vs. 2.8, P=0.18), and instrument conflicts (3.1 vs. 4.0, P=0.054). In the ex vivo setting, both techniques were comparable for achieving a good dissection, although TAMIS failed to prove effective in suturing the rectal wall. Moreover, TEM was significantly quicker despite the small groups and was better appreciated by the surgeons.