Learning curve analysis of transvaginal natural orifice transluminal endoscopic surgery in treating ovarian cysts: a retrospective cohort study

Background Transvaginal Natural Orifice Transluminal Endoscopy (vNOTES) is regarded as a challenging surgical technique to learn but is promising in reducing perioperative pain and significantly improves the cosmetic outcomes. Previous studies on the learning curve analysis of vNOTES mainly focuses on the hysterectomy approach, while the vNOTES ovarian cystectomy's learning curve was merely reported though more frequently performed than vNOTES hysterectomy. Therefore, this study seeks to analyze the learning curve of three surgeons with varying levels of experience in performing endoscopic surgery and vaginal surgeries for the treatment of ovarian cysts using vNOTES. Methods A total of 127 patients with ovarian cysts of a variety of pathological types were treated by ovarian vNOTES performed by three surgeons of different levels of endoscopic and transvaginal surgical experience. Each surgeon's learning curve was plotted using the Cumulative Sum method and divided into three or four phases of technique learning at the turning point of the learning curve. The sociodemographic and clinical features of patients in each phase were then compared and factors potentially associated with operation time were also screened. Results The learning curve was presented in four phases. The operation time (OT) was significantly shorter in phases II (53.66 +/- 16.55 min) and IV (54.39 +/- 23.45 min) as compared with phases I (68.74 +/- 15.85) and III (75.93 +/- 30.55) (p < 0.001). More cases of serve pelvic adhesion and endometrioma were assigned in the later phases. The OT of endometriotic cysts had much longer than that of non-endometriotic cysts(62.57 +/- 18.64 min vs. 49.88 +/- 14.26 min, p = 0.15) The presence of pelvic adhesion [adjusted odds ratio (OR) 7.149 (0.506, 13.792), p = 0.035] and bilateral cyst [adjusted OR 16.996 (2.155, 31.837), p = 0.025], max diameter of cyst[adjusted OR 2.799 (0.174, 5.425), p = 0.037], and individual surgeon [adjusted OR -6.118 (-11.814, -0.423), p = 0.035] were significantly associated with OT. Conclusion There learning curve of ovarian vNOTES has four phases. ovarian vNOTES could be mastered after performing seven, nine, and 16 cases by surgeons #1, 2 and 3 respectively, in gynecologic endoscopic surgeries.