Steep Trendelenburg Positioning in gasless vNOTES Procedures: A Retrospective Study

Objective This retrospective cohort study evaluated the non-inferiority of reduced Trendelenburg positioning (≤ 20°) compared to conventional steep angles (≥ 30°) in gasless transvaginal natural orifice transluminal endoscopic surgery (vNOTES) for benign gynecologic conditions, focusing on perioperative outcomes. Methods 102 patients undergoing gasless vNOTES were stratified into Low- Angle Group (< 30°, mean 20.1°; n = 52) and Steep-Angle Group (≥ 30°, mean 30.8°; n = 50). Primary outcomes included hemodynamics, airway pressure, and conversion rates; secondary outcomes encompassed operative metrics, anesthetic consumption, and 24-h VAS pain scores.Statistical analyses utilized longitudinal mixed models and t-tests. Results The estimation results showed that there is no statistically significant difference between the Low-Angle Group and the Steep-Angle Group in terms of HR, DBP, SBP and airway pressure at different time point during surgery. Airway pressures maintained strict proportionality to tidal volumes in both groups (12–17 cmH ₂ O, p  = 0.72).No significant differences were found between groups in conversion rates (4.0% vs. 4.3%, p = 0.319), operative/anesthesia duration, blood loss, complications, or most recovery indicators. Anesthetic consumption and VAS scores for shoulder pain/PONV were also similar at 2h and 24h. The Low-Angle Group had significantly lower 24-h abdominal pain VAS (0.46 ± 0.28 vs. 1.12 ± 0.42, p = 0.014), exceeding MCID thresholds. Conclusion Performing gasless vNOTES with ≤ 20° Trendelenburg achieves outcomes equivalent to ≥ 30°, including surgical exposure and safety, while significantly reducing postoperative abdominal pain. This challenges the need for routine steep positioning, establishing ≤ 20° as a viable patient-centered standard, offering equivalent efficacy with less discomfort. Further validation warranted.