Comparative study of NOTES rectosigmoidectomy in a swine model: E-NOTES vs. P-NOTES

Background and study aims: Several reports have demonstrated the safety of pure natural-orifice transluminal endoscopic surgery (P-NOTES) using transanal endoscopic microsurgery (TEM) and embryonic NOTES (E-NOTES; laparoscopic surgery through the umbilicus). This study was performed to compare the safety and applicability of NOTES rectosigmoidectomy between E-NOTES and P-NOTES in a swine model. Patients and methods: E-NOTES was conducted through a single port using laparoscopic instruments (n = 11). P-NOTES was performed using TEM with transgastric endoscopic assistance (n = 11). Gastrotomies were created using a needle knife and the balloon dilatation technique, and closed using T-anchors. Blood samples were collected to evaluate changes in systemic cytokine levels during the preoperative and postoperative periods; operative outcomes were also evaluated and compared between the groups. The necropsy findings were recorded after sacrifice at 1 week after the procedure. Results: The mean operative time for P-NOTES was significantly longer than that for E-NOTES (239 vs. 103 minutes, P < 0.001). The mean distance from the anal verge to colorectal anastomosis in the P-NOTES group was significantly less than that in the E-NOTES group (2.9 vs. 17.6 cm, P < 0.001). On necropsy, the complication rate of P-NOTES was higher than that of E-NOTES, but without statistical significance (54.5% vs. 18.2%, P = 0.091). The differences in changes in TNF-alpha, C-reactive protein, interleukin-6, and interleukin-1 beta between P-NOTES and E-NOTES were not significant. Conclusions: E-NOTES rectosigmoidectomy in the swine model is safe, but remains challenging for use in pelvic dissection. P-NOTES rectosigmoidectomy using TEM may be a promising tool for pelvic dissection, but the transgastric approach involves a high degree of risk.