The Effect of Reusable Flexible Ureteroscope Aging on the Efficacy and Safety of Retrograde Intrarenal Surgery.

Purpose: Reusable flexible ureteroscopes may lose their mechanical functionality through overuse, which is known as "aging of the flexible ureteroscope." Although mechanical deterioration has been shown in several studies, the data about the effect of this situation on the efficacy and safety of retrograde intrarenal surgery (RIRS) are missing. The aim of our study was to evaluate the effect of the aging of flexible ureteroscopes on the efficacy and safety of RIRS. Methods: Patients who had undergone RIRS between 2017 and 2021 at a single center were retrospectively included in the study. Serial surgeries were performed using the same reusable flexible ureteroscope (Storz X₂) until it was broken or malfunctioned because of the aging process. Group 1 was formed by the first 10 cases on whom the flexible ureteroscopes were used, representing the youngest period of the instruments, whereas group 2 was composed of the last 10 cases on whom the flexible ureteroscopes were used, representing the oldest phase of the instruments. The operative and postoperative data-including the operation time, hospitalization time, intraoperative complications, postoperative complications, and stone-free rates-were compared between the two groups. Results: A total of five flexible ureteroscopes were included in the study. The number of cases for each flexible ureteroscope ranged between 87 and 133, with a median number of 107 cases. The demographic and clinical properties of patients in both groups were similar. The operation time, lasering time, and total laser pulse were similar between the groups. The stone-free rates in group 1 and group 2 were 82.0% and 78.0%, respectively (p = 0.304). The complication rates were also similar between the groups (p = 0.591). Conclusion: The aging of reusable flexible ureteroscopes did not negatively affect the efficacy and safety of RIRS. Therefore, surgeons may use the reusable types of flexible ureteroscopes until they are totally broken.