This study tests a 100-μm-core fiber with 300-μm-diameter ball tip during Thulium fiber laser (TFL) lithotripsy.
The TFL was operated at 1908 nm wavelength with 35-mJ pulse energy, 500-μs pulse duration, and 300-Hz pulse
rate. Calcium oxalate/phosphate stone samples were weighed, laser procedure times measured, and ablation rates
calculated for ball tip fibers, with comparison to bare tip fibers. Photographs of ball tips were taken before and after
each procedure to observe ball tip degradation and determine number of procedures completed before need to
replace fiber. Saline irrigation rates and ureteroscope deflection were measured with and without TFL fiber present.
There was no statistical difference (P > 0.05) between stone ablation rates for single-use ball tip fiber (1.3 ± 0.4
mg/s) (n=10), multiple-use ball tip fiber (1.3 ± 0.5 mg/s) (n=44), and conventional single-use bare tip fibers (1.3 ±
0.2 mg/s) (n=10). Ball tip durability varied widely, but fibers averaged > 4 stone procedures before decline in stone
ablation rates due to mechanical damage at front surface of ball tip. The small fiber diameter did not impact
ureteroscope deflection or saline flow rates. The miniature ball tip fiber may provide a cost-effective design for safe
fiber insertion through the ureteroscope working channel and the ureter without risk of scope damage or tissue
perforation, and without compromising stone ablation efficiency during TFL ablation of kidney stones.