Abstract

Laser lithotripsy involves thermal risks due to heat generated in the surrounding fluid. The concept of thermal dose, which accounts for both temperature and exposure duration, provides a more nuanced understanding of tissue tolerance than fixed temperature thresholds, considering both the magnitude of the temperature increase and the length of exposure to each specific temperature. The concept of a thermal safety distance defines the spatial extent of potential damage, supporting safe power limits of 10 W in the ureter and 20 W in the kidney. Importantly, the type of laser (holmium:YAG, thulium fiber, or thulium:YAG) does not independently affect the rise in temperature, which is primarily driven by the amount of energy absorbed by water in the surrounding tissue. Temperature-related tissue injury can be mitigated by optimizing the flow of the irrigation fluid and the laser power settings and activation patterns. Patient summary: Laser treatment for stones in the kidney or ureter generates heat, which can harm adjacent tissues. The use of low-power settings and proper fluid flow helps in reducing this risk. © 2025 European Association of Urology