Due to the high cost and fragility of the reusable digital flexible ureterorenoscopes (fURSs), several single use alternatives have emerged. The goal of our in-vitro study was to determine the deflection properties of these scopes with the working channel empty and occupied by different accessories.
Four single-use (LithoVue, Boston Scientific, USA; Pusen, China; Neoflex, Neoscope, USA; YouCare Tech, China) and four reusable (URF-V2, Olympus, Japan; Flex Xc, Karl Storz, Germany; Cobra vision and Boa vision, Richard Wolf, Germany) fURSs were compared in a total of 10 different settings.
The maximal up and down deflection was measured with the working channel empty and then occupied with various tools (200µm, 273µm, 365µm laser fibres; 1.5Fr, 1.9Fr, 2.2Fr baskets; 0.038” PTFE, 0.035”Terumo guidewires; Piranha biopsy forceps). Each measurement was performed three times. Deflection angles were calculated using a protractor. A scoring system by adding the total deflection degrees for each scope and each setting was used to compare the fURSs.
When the channel was occupied, the most cumulative deflection was achieved by NeoFlex (5043º) and the least by YouCare Tech (3912º) (Fig.1,2). The least affect on deflection was caused by the 200µm laser fibre (2198º) for the disposable fURSs, and by 1.5 Fr basket (1971º) for the reusable fURSs. In both reusable and disposable fURSs, the PTFE guidewire caused the maximum impact on scope deflection (Fig.3).
Overall, single-use fURSs had better deflection in most settings, except when 365 µm laser fibre or guidewires (both PTFE and nitinol) were occupying the working channel (Fig.3).
The single-use fURSs seem to have better in-vitro deflection than the reusable scopes. But when thicker, less flexible tools occupied the working channel, the reusable fURSs deflected better. Further evaluation of our findings in clinic settings will help to confirm our findings.