Background and Purpose: Ureteroscope breakage is commonly related to laser fiber damage. Often, the damage is mechanical and not energy related. As such, we evaluated a novel laser fiber and sheath system in preventing mechanical ureteroscope damage during fiber insertion. Materials and Methods: We assessed 200-μm/272/3-μm laser fibers with the laser sheath in a flexible ureteroscope. Diminishment of active deflection and irrigation flow rates were compared with a standard laser fiber alone. Eight nonassembled working channel components were tested in a 0-degree/90-degree/210-degree deflection model. After insertion cycles, external and endolumenal damage to the working channel were classified. We also tested the sheath system in a 0-degree/90-degree/210- degree deflection model for fiber failure and laser damage. Results: In all test trials with the sheath and for standard laser fibers in the 0-degree model, there were no channel perforations or damage. With standard laser fibers, in the 210-degree model, superficial scratches and demarcated abrasions were visible after 10 and 60 to 70 insertions for the 273-μm laser fiber and after 30 insertions (superficial scratches) for the 200-μm laser fiber. In the 90-degree model, superficial scratches occurred after 20 insertions for the 273-μm fibers and after 40 insertions for the 200-μm laser fibers. No demarcated abrasions were seen after 100 insertions. In the 210-degree model, there was one perforation with the 272-μm fiber, but none with 200-μm fiber. There were no fiber failures with sheath use; however, the sheath did not prevent laser energy damage. The laser sheath resulted in a 4.7-degree/3.8-degree (1.2%/1.5%) diminishment in deflection (up/down) for the 200 μm and a 3.5-degree/4.3-degree (1.8%/1.5%) diminishment for 272-μm laser fiber compared with standard 200/272-μm laser fiber. Irrigation flow was diminished with the sheath on both the 200-μm and 272-μm laser fiber by 28.7% and 32.6%, respectively. Conclusion: The Scope Guardian Sheath prevented mechanical working channel damage with minimal diminishment of deflection and irrigation flow.
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