Presented by: Jia-Lun Kwok MBBS, FRCS(Urol)(Glasg)
Department of Urology, University Hospital Zurich, University of Zurich, Zurich, Switzerland ; Department of Urology, Tan Tock Seng Hospital Singapore, Singapore

Introduction

Recently, the novel pulsed thulium:yttrium-aluminum-garnet (p-Tm:YAG) laser has been introduced for clinical use. Studies found in literature so far present promising results on p-Tm:YAG ablation efficiency, although all were based on artificial stone models (eg. BegoStone) – not on human urinary stones. The aim of the present study was to evaluate the p-Tm:YAG ablation efficiency with human urinary stones.

Materials

Two human urinary stone compositions were subjected to laser lithotripsy using a p-Tm:YAG laser generator (Thulio® ,Dornier MedTech GmbH®, Wessling, Germany): calcium oxalate monohydrate (COM) and uric acid (UA). A cumulative energy of 200 J was applied to each stone using one of three laser settings: 0.1J x 100Hz, 0.4J x 25Hz, and 2.0J x 5Hz (average power 10W). After lithotripsy, stone samples were passed through a laboratory sieve with a 250 µm mesh size opening. Ablated stone mass was calculated from the difference in weight between the pre-lithotripsy stone and post-lithotripsy remnant fragments > 250 µm. Ablation efficiency was defined as ablated stone mass per unit of energy applied (mg/J).

Results

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Mean ablation efficiency was 0.04, 0.06, 0.07 mg/J (COM) and 0.04, 0.05, 0.06 mg/J (UA) for each of the above laser settings, respectively. When considering laser settings, there was no significant difference in ablation efficiency between any of the settings for both COM and UA (ANOVA p=0.08 and p=0.11, respectively). Likewise, when considering stone composition within each laser setting, there was no significant difference in ablation efficiency between both composition types COM and UA (0.1J x 100Hz: p=0.89, 0.4J x 25Hz: p=0.22, 2.0J x 5Hz: p=0.45). There was however a non-significant pattern of better ablation efficiency for COM as compared to UA.

Conclusion

To the best of our knowledge, this is the first study showing ablation efficiency of the p-Tm:YAG laser on human urinary stones. The p-Tm:YAG appears to ablate COM and UA stones equally well, with no significant differences between differing laser settings.

Funding

None

Co-Authors

Eugenio Ventimiglia, MD, FEBU
Division of Experimental Oncology/Unit of Urology, Urological Research Institute, IRCCS Ospedale San Raffaele, Milan, Italy ; Young Academic Urologists (YAU), Endourology & Urolithiasis Working Group, Arnhem, The Netherlands; Progressive Endourological Association for Research and Leading Solutions (PEARLS)

Vincent De Coninck, MD, FEBU
Department of Urology, AZ Klina, Brasschaat, Belgium ; Young Academic Urologists (YAU), Endourology & Urolithiasis Working Group, Arnhem, The Netherlands ; Progressive Endourological Association for Research and Leading Solutions (PEARLS)

Yazeed Barghouthy, MD
Department of Urology, Centre Hospitalier de Valenciennes, Valenciennes, France ; Progressive Endourological Association for Research and Leading Solutions (PEARLS)

Alexandre Danilovic, MD
Department of Urology, Universidade de São Paulo Hospital das Clínicas - HCUSP, Department of Urology, Hospital Alemão Oswaldo Cruz, São Paulo, Brazil ; Progressive Endourological Association for Research and Leading Solutions (PEARLS)

Anil Shrestha, MD
Department of Urology, National Academy of Medical Sciences, Bir Hospital and B&B Hospital, Gwarko Lalitpur, Nepal ; Progressive Endourological Association for Research and Leading Solutions (PEARLS)

Niamh Smyth, MD
University Hospital Monklands, Monkscourt Avenue, Airdrie, ML60JS, United Kingdom ; Progressive Endourological Association for Research and Leading Solutions (PEARLS)

Florian Schmid, MD, FEBU
Department of Urology, University Hospital Zurich, University of Zurich, Zurich, Switzerland

Manuela Hunziker, MD, FEBU
Department of Urology, University Hospital Zurich, University of Zurich, Zurich, Switzerland

Cédric Poyet, MD, FEBU
Department of Urology, University Hospital Zurich, University of Zurich, Zurich, Switzerland

Michel Daudon, MD
Sorbonne Université, Hôpital Tenon, CRISTAL Laboratory, Paris, France

Olivier Traxer, MD
Sorbonne Université, GRC n°20, Groupe de Recherche Clinique sur la Lithiase Urinaire, Hôpital Tenon, F-75020 Paris, France ; Progressive Endourological Association for Research and Leading Solutions (PEARLS)

Daniel Eberli, MD, FEBU
Department of Urology, University Hospital Zurich, University of Zurich, Zurich, Switzerland

Etienne Xavier Keller, MD, FEBU
Department of Urology, University Hospital Zurich, University of Zurich, Zurich, Switzerland ; Young Academic Urologists (YAU), Endourology & Urolithiasis Working Group, Arnhem, The Netherlands ; Progressive Endourological Association for Research and Leading Solutions (PEARLS)