The Best Laser: Holmium:YAG

How to cite: Humphreys MR. “The Best Laser: Holmium:YAG.” Grand Rounds in Urology. November 13, 2025. Accessed Feb 2026. https://grandroundsinurology.com/the-best-laser-holmiumyag/

Summary

Michell R. Humphreys, MD, Department of Urology Chair, Professor of Urology, Mayo Clinic, Phoenix, Arizona, makes the case that Holmium: YAG remains the best laser platform in endourology, despite growing interest in thulium fiber laser (TFL) technology. He argues that while newer systems offer incremental advantages in specific settings, Holmium:YAG provides unmatched versatility, safety, and reliability across stone types and urologic applications.

Dr. Humphreys begins the presentation with a concise review of laser physics relevant to lithotripsy, focusing on wavelength-dependent water absorption and the three adjustable laser parameters: pulse energy, frequency, and pulse width. He explains how these variables influence photothermal and photomechanical effects, stone fragmentation, retropulsion, and tissue interaction.

Holmium:YAG with pulse modulation technology, including MOSES 2.0, is highlighted for its ability to reduce retropulsion and improve efficiency by optimizing bubble dynamics at the stone surface. In contrast, while TFL systems operate at higher frequencies and demonstrate efficient ablation in bench studies, they exhibit important limitations related to stone composition and thermal safety.

Clinical evidence is reviewed for a comparison of Holmium:YAG and TFL. Meta-analyses and randomized trials demonstrate no meaningful differences in stone-free rates or complication rates. When pulse-modulated Holmium:YAG is included, outcomes often favor Holmium in efficiency metrics. Particular attention is given to calcium phosphate and brushite stones, where TFL is associated with stone charring, melting, and reduced fragmentation efficiency.

Thermal safety is a major focus. Data show that high-frequency TFL settings can rapidly exceed tissue injury thresholds, resulting in significantly higher peak temperatures than with Holmium:YAG. A multicenter European experience is discussed in which elevated ureteral stricture rates were observed early in TFL adoption, correlated with higher energy and power settings.

Dr. Humphreys argues that while TFL has a role in select applications, Holmium:YAG remains the most versatile and dependable laser, capable of treating all stone types, benign prostatic hyperplasia, strictures, soft tissue, and upper tract tumors with a well-established safety profile.

About the 32nd Annual Perspectives in Urology: Point Counterpoint conference: Presented by Program Chair and Grand Rounds in Urology Editor-in-Chief E. David Crawford, MD, this conference brought together leading experts in urology, medical oncology, and radiation oncology to discuss and debate the latest topics in genitourinary cancers, primarily prostate cancer and bladder cancer. This interactive conference offered topical lectures, pro/con debates, interesting-case presentations, interactive panel discussions, and interactive audience and faculty networking.