Comparison of Flexible Ureterorenoscope Quality of Vision : an in Vitro Study

Introduction: Flexible ureterorenoscopy (fURS) is one of the best solutions for treatment of renal calculi <2 cm and for upper urinary tract urothelial carcinoma conservative treatment. An adequate quality of vision is mandatory to help surgeon get better outcomes. No studies have been done, to our knowledge, about what fURS in the market has the best quality of vision. Materials and Methods: Seven different fURS were used to compare the image quality (Lithovue, Olympus V, Olympus V2, Storz Flex XC - in White Light and in Clara+Chroma mode - Wolf Cobra Vision, Olympus P6, and Storx Flex X2). Two standardized grids to evaluate contrast and image definition and three stones of different composition were filmed in four standardized different scenarios. These videos were shown to 103 subjects (51 urologists and 52 nonurologists) who had to evaluate them with a rating scale from 1 (very bad) to 5 (very good). Results: No difference in terms of scores was observed for sex of the participants. Digital (D) ureterorenoscopes were rated better than fiber optics (FOs) ureterorenoscopes. Overall, Flex XC White Light and XC Clara+Chroma image quality resulted steadily better than other fURS (p < 0.0001). Olympus V generally provided a vision better than Lithovue. Cobra Vision and Olympus V2 had superimposable values that were significantly lower than Lithovue's ones. Olympus P6 and Storz X2 offered a low quality of vision compared to the others. In the medium simulating bleeding, Olympus V and V2 significantly improved their scores of 12% and 8.1%, contrary to rest of the ureterorenoscopes. Conclusion: D ureterorenoscopes have a better image quality than FO ones. The only disposable ureterorenoscope tested was comparable to the majority of other D ureterorenoscopes. The best image quality was provided by Storz D ureterorenoscopes, being Clara Chroma the favorite Spies Mode, according to literature.