An in Vitro Comparative Assessment of Single-Use Flexible Ureteroscopes Using a Standardized Ureteroscopy Training Model

Introduction: Perceived benefits like decreased contamination rates and reduced postoperative incidence of complications after urolithiasis surgery have led to increased adoption of single-use flexible ureteroscopes (su-fURS). Using a validated, standardized simulator model with enhanced "fluoroscopic" capabilities, we performed an in vitro comparative assessment of four commercially available models of su-fURS. Both objective and subjective parameters were assessed in this study.

Methods: Two standardized tasks, (1) exploration of the model's kidney collecting system and (2) repositioning of a stone fragment from the upper renal to lower renal pole were assigned to participants, who performed these tasks on all four scopes. Four models of su-fURS (Boston LithoVue, PUSEN PU3033A, REDPINE, INNOVEX EU-ScopeTM) were assessed, with task timings as end-points for objective analysis. Cumulative "fluoroscopic" time was also recorded as a novel feature of our enhanced model. Post-task questionnaires evaluating specific components of the scopes were distributed to document subjective ratings.

Results: Both subjective and objective performances (except stone repositioning time) across all four su-fURS demonstrated significant differences. However, objective performance (task timings) did not reflect subjective scope ratings by the participants (Rs < 0.6). Upon Kruskal-Wallis H test with post hoc analyses, REDPINE and INNOVEX EU-ScopeTM were the preferred su-fURS as rated by the participants, with overall scope scores of 9.00/10 and 9.57/10.

Conclusions: Using a standardized in vitro simulation model with enhanced fluoroscopic capabilities, we demonstrated both objective and subjective differences between models of su-fURS. However, variations in perception of scope features (visibility, image quality, deflection, maneuverability, ease of stone retrieval) did not translate into actual technical performance. Eventually, the optimal choice of su-fURS fundamentally lies in individual surgeon preference, as well as cost-related factors.