Optimal deflection techniques for flexible and navigable suction ureteral access sheaths (FANS): a comparative in vitro PEARLS analysis.

Flexible and navigable suction ureteral access sheaths (FANS) have been introduced without current evidence on how to optimize deflection. Aim was to evaluate in vitro deflection angles with 2 different FANS techniques-sheath advancement and ureteroscope deflection; and effects of sheath size-ureteroscope combinations.

We evaluated in vitro deflection angles of 10/12Fr, 11/13Fr and 12/14Fr FANS (Hunan Reborn Medical Co. Ltd) with six single-use flexible ureteroscopes (Pusen Uscope 7.5Fr, OTU WiScope 7.5Fr, OTU WiScope 8.6Fr, Innovex EU-scope 8.7Fr, Red Pine RP-U-C12 8.7Fr and Boston Scientific Lithovue 9.5Fr). Two deflection techniques were tested: (1) sheath advancement-advancing the sheath forward over a maximally deflected ureteroscope, and (2) ureteroscope deflection-maximally deflecting the ureteroscope from various starting positions relative to tip of the sheath.

Intra and inter-scope comparisons of maximum deflection angles were significantly different (all ANOVA p < 0.01). Largest maximum angles for all ureteroscopes were with the sheath advancement technique (range 218°-277°), and second largest for most scopes using the ureteroscope deflection technique at tip (range 111°-212°), mostly deviating from manufacturer specifications (range 270°-275°). 10/12Fr and 11/13Fr sheath sizes were more flexible than 12/14Fr. Largest angles were with 11/13Fr sheath-OTU8.6Fr/Innovex8.7Fr combinations.

Optimal deflection with FANS is achieved using either a sheath advancement technique, or ureteroscope deflection technique at tip. Despite using these optimized techniques, deflection angles specified by manufacturers seem hardly achievable. The sheath advancement technique and 11/13Fr sheath-OTU8.6Fr/Innovex8.7Fr combinations may be better suited for lower pole situations. Urologists should be aware of these differences and apply the findings to their FANS technique.

World journal of urology. 2024 Oct 30*** epublish ***

Alex Lua, Lynnette R L Tan, Frédéric Panthier, Alba Sierra, Eugenio Ventimiglia, Catalina Solano, Vincent De Coninck, Steffi Kar Kei Yuen, Vineet Gauhar, Olivier Traxer, Etienne Xavier Keller, Jia-Lun Kwok

Department of Urology, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, 308433, Singapore., Progressive Endourological Association for Research and Leading Solutions (PEARLS), Paris, France., Department of Surgery, SH Ho Urology Centre, The Chinese University of Hong Kong, Hong Kong, China., Department of Urology, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, 308433, Singapore. .