Clinical Evaluation of Miniature Flexible Scope for Diagnosis of Ureteroscope Working Channel Defects

Introduction: To evaluate flexible ureteroscope working channels with a 1.06 mm digital borescope (Clarus Medical, Minneapolis, MN) and identify factors contributing to ureteroscope damage over time.Materials and Methods: We performed a single institutional prospective study of patients undergoing stone surgery using a nondisposable flexible ureteroscope. A 1.06 mm borescope was used to evaluate ureteroscopes before and after surgery. Borescope videos were reviewed by two independent researchers to quantify average pre- and postprocedural damage.Results: Twenty-five procedures were performed with pre- and postprocedural borescope assessment between August 2021 and February 2022. All patients received preoperative CT imaging depicting a mean axial stone size of 14.1 +/- 8.4 mm and density of 923.4 +/- 458.1 HU. Mean operative time was 63.8 +/- 34.0 minutes. The average number an instrument passes through the working channel was 2.1 +/- 1.6. Laser was used in 11 cases with mean laser time of 18.8 +/- 19.7 minutes and mean total energy of 5.8 +/- 4.2 KJ. On preoperative assessment, all ureteroscopes had some form of defect (24% shave, 32% pinhole, 96% dents and scratches, and 28% discolorations). During postoperative assessment, 23/25 (92%) ureteroscopes showed additional damage with an average of 3.7 +/- 2.8 imperfections acquired after one use. Significant differences were seen in acquired shavings (p = 0.028) and scratches or dents (p = 0.018). Of the 355 imperfections seen on postoperative evaluation, 0.4% were shave, 3% were pinhole, 85.8% were dents and scratches, and 10.8% were discolorations.Conclusion: The Clarus borescope observed defects after the majority of flexible ureteroscopy procedures for nephrolithiasis. Although such disruptions may not immediately render ureteroscopes nonfunctional, they are more common than previously described and could increase maintenance costs. Further studies are needed to investigate the burden of unit damage per procedure to raise operator awareness and reduce preventable ureteroscope imperfections.