Thulium Fiber Laser Damage to the Ureter

Our laboratory is studying experimental thulium fiber laser (TFL) as a potential alternative lithotripter to the clinical gold standard Holmium: YAG laser. Safety studies characterizing undesirable Holmium laser-induced damage to ureter tissue have been previously reported. Similarly, this study characterizes TFL induced ureter and stone basket damage. A TFL beam with pulse energy of 35 mJ, pulse duration of 500 mu s, and pulse rates of 150-500 Hz was delivered through a 100-mu m-core, low-OH, silica optical fiber to the porcine ureter wall, in vitro. Ureter perforation times were measured and gross, histological, and optical coherence tomography images of the ablation zone were acquired. TFL operation at 150, 300, and 500 Hz produced mean ureter perforation times of 7.9, 3.8, and 1.8 s, respectively. Collateral damage averaged 510, 370, and 310 mu m. TFL mean perforation time exceeded 1 s at each setting, which is a greater safety margin than previously reported during Holmium laser ureter perforation studies.