Evaluation of a new 240-µm single-use holmium:YAG optical fiber for flexible ureteroscopy.

BACKGROUND AND PURPOSE: Numerous holmium:yttrium-aluminum-garnet laser fibers are available for flexible ureteroscopy. Performance and durability of fibers can vary widely among different manufacturers and their product lines with differences within a single product line have been reported. We sought to evaluate a newly developed nontapered, single-use 240-µm fiber, Flexiva™ 200 (Boston Scientific, Natick, MA), during clinical use and in a bench-testing model. MATERIALS AND METHODS: A total of 100 new fibers were tested after their use in 100 consecutive flexible ureteroscopic lithotripsy procedures by a single surgeon (B.K.). Prospectively recorded clinical parameters were laser pulse energy and frequency settings, total energy delivered and fibers failure. Subsequently, each fiber was bench-tested using an established protocol. Parameters evaluated for were fibers true diameter, flexibility, tip degradation, energy transmission in straight and 180° bend configuration and fibers failure threshold with stress testing. RESULTS: The mean total energy delivered was 2.20 kJ (range 0-18.24 kJ) and most common laser settings used were 0.8 J at 8 Hz, 0.2 J at 50 Hz, and 1.0 J at 10 Hz, respectively. No fiber fractured during clinical procedures. The true fiber diameter was 450 µm. Fiber tips burnt back an average of 1.664 mm, but were highly variable. With laser setting of 400 mJ at 5 Hz, the mean energy transmitted was 451 and 441 mJ in straight and 180° bend configuration, respectively. Thirteen percent of fibers fractured at the bend radius of 0.5 cm with a positive correlation to the total energy transmitted during clinical use identified. CONCLUSION: Fiber performance was consistent in terms of energy transmission and resistance to fracture when activated in bent configuration. Fiber failure during stress testing showed significant correlation with the total energy delivered during the clinical procedure. The lack of fiber fracture during clinical use may reduce the risk of flexible endoscope damage due to fiber failure.

Prestenting improves ureteroscopic stone-free rates.

PURPOSE: Although the use of stents after ureteroscopy has been studied extensively, relatively little has been published about stent placement before complicated ureteroscopic procedures. In this study, we examined our experience with stent placement before ureteroscopic management of renal and ureteral stone disease. PATIENTS AND METHODS: A total of 90 patients underwent ureteroscopic surgery on 115 renal units by a single surgeon from 2001 to 2006. All patients had documented follow-up with imaging either by CT or intravenous urography (IVU) with tomography. Patients were classified into two groups depending on whether they had a stent placed before ureteroscopy. Baseline characteristics, operative indications for stent placement, stone-free rates, and complications were compared between groups. RESULTS: Baseline characteristics were similar between the groups. The majority of patients received stents before stone management because of technical considerations during surgery (17/36, 47%) or infection (13/36, 37%). Strict stone-free rates after ureteroscopic treatment were 47% in the 79 procedures without previous stents, compared with 67% in the 36 procedures with prestenting (P < 0.05). Including small fragments (2 mm or smaller), stone-free rates improved to 54% v 78%, respectively (P < 0.02). Complications were not significantly different in the two groups (P = 0.70). CONCLUSION: Although routine stent placement is not necessary before all ureteroscopic procedures, we demonstrate that it is associated with good stone-free rates and few complications. In this retrospective cohort, prestenting was associated with significantly higher stone-free rates. Prestenting should be considered in challenging cases.