Assessment of anatomical outcomes in the upper urinary tract following flexible ureteroscopy with flexible and navigable suction ureteral access sheath: 1-year results from a multicentre study.

Introduction: Flexible and navigable suction access sheath (FANS) with flexible ureterorenoscopy (FURS) has demonstrated favourable 30-day and 3-month outcomes for renal stones in normal anatomy. We aimed to investigate the long-term 1-year safety and efficacy of FANS for renal and ureteric stones in normal or anomalous anatomy. Methods: This prospective multicentre study included adults undergoing FURS with FANS across 11 centres in 9 countries (April 2023 to August 2024), with follow-up until August 2025. Anatomical outcomes were assessed by contrast CT (or ultrasound if CT not available) at 1 year; stone-free rate (SFR) was assessed via noncontrast CT at 30 days. The primary aim was to report if altered anatomy, such as pelvicalyceal or pelviureteric or ureteric stricture, occurs at a later stage. Results: Among 288 patients, median age was 55 years, and 4.5% had anomalous renal anatomy. About 49% were prestented. Stones were located only in the kidney (62%), ureter (18%) or both (20.1%). Median stone volume was 725 mm Conclusions: This study reports the longest 1-year follow-up data for patients undergoing FURS with FANS to date. The study did not identify a high rate of late anatomical complications after successful FANS deployment in the treatment of renal and ureteric stones. Caution is warranted in patients with a history of ureteral re-implantation due to elevated risk of stricture formation.