Pulsed thulium laser outpaces holmium in bench and simulator stone tests

A benchtop, ex vivo and simulator study published in BMC Urology compared a pulsed thulium: YAG (p-Tm: YAG) laser with the conventional holmium: YAG (Ho: YAG) laser for laser lithotripsy inside a flexible navigable suction access sheath (FANS) environment. The study, led by Min Liu and colleagues with Xiaofeng Gao as senior author, was published on 19 October 2026 as an open access research article. Both lasers were tested with 272-micrometer fibers, the fiber size used across all experimental settings.

The laboratory work used two stone models. Die-Stone phantoms and human calcium oxalate monohydrate (COM) stones were ablated with each laser platform. Fragment sizes were sorted with a sequential dual-sieve benchtop model using 3.0 mm and 0.5 mm screens, allowing the researchers to quantify the total ablation rate (St) and the dusting rate (Sd), the latter representing material reduced below 0.5 mm. Across all tested settings, p-Tm: YAG produced higher total ablation and dusting rates than Ho: YAG.

The differences were most clearly reported at the 20 W setting on phantom stones. There, p-Tm: YAG achieved a total ablation rate of 2.49 ± 0.39 mg/s versus 1.52 ± 0.32 mg/s for Ho: YAG (p = 0.031), and a dusting rate of 1.97 ± 0.26 mg/s versus 0.98 ± 0.17 mg/s (p = 0.007). Proportional analysis showed that p-Tm: YAG reached a peak dusting fraction, meaning fragments smaller than 0.5 mm, of 79%.

The human COM stone experiments showed a similar pattern. With these natural stones, p-Tm: YAG maintained a 2.6-fold higher total ablation rate and a 3.3-fold higher dusting rate than Ho: YAG. The dusting proportion was 51.0% for p-Tm: YAG compared with 42.7% for Ho: YAG, indicating that a larger share of the ablated stone material ended up as fine dust rather than larger fragments requiring retrieval.

To assess performance in a more procedure-oriented setting, the team used a urological simulator equipped with an 11/13-Fr FANS and a 7.5-Fr flexible ureteroscope. They compared operative time, cumulative lasering time (CLT) and operative efficiency between the two laser platforms. In this simulator model, p-Tm: YAG achieved significantly greater procedural efficiency, measured at 0.53 ± 0.01 mg/s versus 0.41 ± 0.05 mg/s for Ho: YAG (p = 0.039).

The authors conclude that integrating p-Tm: YAG with FANS technology may improve procedural efficiency by balancing accelerated ablation with high-volume dusting, and they state that these findings support further evaluation of p-Tm: YAG in FANS-assisted flexible ureteroscopy. Flexible ureteroscopy and FANS, along with pulsed thulium: YAG lasers, are described in the study as important recent advancements in the endourological treatment of urinary stones.

Several limitations of scope should be kept in view when interpreting these results. The work was conducted on phantom stones, ex vivo human COM stones and a surgical simulator rather than in living patients, and the article is listed with a clinical trial number of “not applicable.” Simulator efficiency and benchtop ablation rates are model estimates of procedural performance, not demonstrated clinical outcomes, and the published version is an early-access author manuscript that remains subject to further editing before the final Version of Record.

The findings add to a growing body of comparative literature on thulium-based laser platforms in stone treatment, including recent systematic reviews and meta-analyses comparing thulium fiber and pulsed thulium: YAG systems with holmium: YAG for ureteroscopic lithotripsy. Within that landscape, this study’s contribution is a controlled, multi-model comparison of ablation and dusting performance specifically framed around the FANS environment, where suction of dust and fragments is a central part of the technique.

For clinicians following laser lithotripsy technology, the reported numbers suggest that, under the tested bench and simulator conditions, pulsed thulium: YAG ablated stone material faster and produced a larger fraction of sub-0.5 mm dust than holmium: YAG at equivalent power settings. Whether that laboratory and simulator advantage translates into shorter operations, fewer auxiliary procedures or better stone-free outcomes for patients will depend on the further clinical evaluation the authors call for.

Subject of Research: Comparison of pulsed thulium: YAG and holmium: YAG lasers for stone ablation in a flexible navigable suction access sheath environment

Article Title: Pulsed thulium: YAG versus holmium: YAG in a flexible navigable suction access sheath environment: a bench, Ex Vivo, and simulator study

Article References: Liu, M., Chen, M., Li, C., Dong, H., Fang, Z., Ying, Z., Zhang, S., Li, L., Peng, Y., Lu, Y., & Gao, X. (2026). Pulsed thulium: YAG versus holmium: YAG in a flexible navigable suction access sheath environment: a bench, Ex Vivo, and simulator study. BMC Urology. https://doi.org/10.1186/s12894-026-02373-1

Image Credits: AI Generated

DOI: 10.1186/s12894-026-02373-1

Keywords: pulsed thulium: YAG, holmium: YAG, laser lithotripsy, flexible ureteroscopy, suction access sheath, FANS, kidney stones, calcium oxalate monohydrate, dusting, ablation rate, urological simulator, BMC Urology