Multimodal comparison of 19 single-use flexible ureteroscopes: bench testing, operative video assessment, and surgeon...

Single-use flexible ureteroscopes (fURSs) differ substantially in optical and mechanical properties, yet comparative evidence remains limited. We performed a multimodal in vitro and clinical assessment of 19 commercially available single-use fURSs to quantify performance variability and examine which device characteristics are associated with surgeon-reported usability.

Each of 19 models was bench-tested for field of view, laser-fiber safety distance, irrigation flow, deflection, image resolution, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and color discrimination. One surgeon used each device in three separate patients (57 procedures total) and completed a standardized questionnaire after every case; three blinded reviewers scored anonymized intraoperative video. As a secondary analysis, device-level bench metrics were related to patient-level outcomes using a permutation test with correction for multiple comparisons.

All domains showed marked variability (resolution 0.447-0.826 lp/mm; baseline deflection 219-312°, lowest 134° with accessories; empty-channel irrigation 27.9-39.0 mL/min; field of view 75-110°). In secondary, exploratory analysis, no bench metric showed an association with surgeon-reported or video-based outcomes surviving correction for multiple comparisons (54 tests, minimum q = 0.20).

Contemporary single-use fURSs show substantial heterogeneity, and no single device excelled across every domain. Device selection should weigh several performance characteristics against the intended clinical scenario; whether bench performance predicts surgeon-reported usability remains unresolved and warrants larger, adequately powered studies.