Increased efficacy in lower pole stone management with a novel flexible and navigable suction ureteral access sheath with flexible ureteroscopic lithotripsy: a case series.

Background: The flexible and navigable suction ureteral access sheath (FANS-UAS) is regarded as a complement to flexible ureteroscopy in retrograde intrarenal surgery. Management of lower pole stones (LPS) is challenging due to the difficulty of anatomical access to the inferior renal calyx. Case Description: The novel FANS-UAS (11/13.5 Fr; 40/50 cm length; 7 cm navigable tip length; 180° angulation) from Well Lead Medical (Guangzhou, China) has been commercially-available in July 2024 and first-used in The University of Hong Kong-Shenzhen Hospital. This case series included five candidates (three males; mean age 37.8±15.1 years) with LPS (max. diameter 7-10.5 mm) undergoing FANS-UAS with flexible ureteroscopic lithotripsy. Success rate of FANS-UAS catheterization was 80% as a male patient displayed poor ureter elasticity intraoperatively and the operation had to be completed with a 10/12 Fr tip-flexible UAS and stone basket. LPS, including those with an infundibulopelvic angle <30°, could be easily navigated and removed with insignificant to no residual stones remaining. No stone basket was used. Grade I and II ureteric injuries occurred in two separate patients that were resolved upon four weeks of ureteral stenting. No significant intra- and post-operative complication was observed. The mean total operative duration was 66.5±22.6 minutes. Computed tomography scans were conducted at day one post-operation. Among the cases with successful FANS-UAS insertion, the absolute and relative stone free rate, defined as complete absence and absence of residual fragments <2 mm, was 75% and 100%, respectively. All patients remained stone-free at one-month follow-up with no adverse events. Conclusions: Early outcomes of the novel 11/13.5 Fr FANS-UAS applied successfully on four patients demonstrate its feasibility, safety, and efficiency in removing LPS. However, improvements in design may be necessitated in the future. For the meantime, prolonged follow-up and larger patient samples are necessitated to further elucidate its outcomes and prognosis.