Effective ureteral access sheath insertion during flexible ueteroscopy: Influence of the ureteral orifice configuration

We sought to determine the possible predictors for effective insertion of the ureteral access sheath (UAS) during flexible ureteroscopy (fURS) in virgin ureters and its impact on postoperative ureteral wall injury and the procedural outcome. A retrospective review of prospectively collected data was performed for all consecutive patients scheduled for fURS of virgin ureters at two tertiary care centers between 2018 and 2020. Demographics, stone characteristics, and perioperative data, including the configuration of the ureteral orifice (UO) over introductory guidewire insertion, were collected. Multivariate logistic regression was used to detect possible predictors of successful UAS insertion. In total, 128 patients who underwent primary fURS were included, with a mean age of 43.3±12.3 years and a stone burden of 12.3±6.9 mm. One hundred and seven patients (85.9%) achieved successful ureteral access insertion, including 81 (63.3%) without ureteral dilatation and 29 (22.7%) out of the 35 (27.3%) patients who needed ureteral dilation. Patients who underwent successful UAS placement into virgin ureters were significantly older and had a lower body mass index. A tent-shaped UO over the guidewire led to successful UAS insertion. In multivariate regression analysis, cases with body mass index (BMI)