Flexible Ureteroscopy and Laser Lithotripsy Using a Flexible and Navigable Ureteral Access Sheath Are Equally Safe and Effective whether Done in a Sitting or a Standing Position: A Multicenter Study by European Association of Urology-Endourology and the Flexible and Navigable Suction Access Sheath Collaborative Group.

Introduction: Flexible ureteroscopy (FURS) using the flexible and navigable suction ureteral access sheath (FANS) is a novel technique for treatment of kidney stones. We aimed to compare outcomes of FURS with FANS in the sitting vs standing position. Patients and Methods: We analyzed adult patients from 21 centers who underwent FURS with FANS, divided according to whether the surgeon operated in a sitting or standing position. Baseline demographics, operative parameters, and 30-day outcomes were compared. Multivariable logistic regression was used to identify potential predictive factors for zero residual fragments (ZRF). Results: There were 457 patients in the sitting group and 247 patients in the standing group. In the sitting group, more patients had the surgical procedure under general anesthesia (p = 0.022). Disposable scopes were preferred in the standing group (p < 0.001). Median lasing and ureteroscopy time were significantly shorter in the siting group, but there was no difference in total surgical time (median 45 vs 46 minutes, p = 0.102). A larger but nonsignificant percentage of grade 1 access sheath insertion injuries were reported in the standing position. Multivariable logistic regression analysis showed that stone volume (odds ratio [OR]: 0.82, 95% confidence interval [CI]: 0.72-0.93, p = 0.003) and operative time (OR: 0.99, 95% CI 0.99-1.00, p = 0.002) but not surgeon position (OR: 1.04, 95% CI: 0.75-1.44, p = 0.82) were significant predictors of ZRF. Procedural safety was not compromised significantly. Conclusions: FURS with FANS is equally safe and effective in the sitting and standing positions. This study provides the impetus to improve FURS ergonomics, especially with the move toward its use in complex and large stones.