Presented by: Crystal Valadon MD, MBA
The University of Kansas Health System

Introduction

Thulium fiber laser (TFL) is widely used in ureteroscopic laser lithotripsy. Computerized tomography (CT) scan is the preferred pre-operative imaging for nephrolithiasis due to its precise stone characteristics. This study examines the relationship between preoperative stone features and cumulative laser energy and time.

Materials

A retrospective multicenter study (01-2020 to 04-2023) included stone-free patients after ureteroscopy using TFL (Soltive™ 60W). Exclusion criteria: pregnancy, age <18, anatomical abnormalities, additional procedures, and missing stone or laser data. Stone measurements were conducted by an experienced urologist at each institution.

Results

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The study included 200 patients. Table 1 displays patient, stone, and peri-operative characteristics. Laser energy showed significant positive correlations with stone size (r=0.59, p<.001), volume (r=0.73, p<.001), density (r=0.44, p<.001), location (r=0.40, p<.001), and ureteroscopic technique (r=0.14, p=0.04). Similarly, these factors significantly impacted laser time, except for ureteroscopic technique (r=0.57, p<.001; r=0.70, p<.001; r=0.38, p<.001; r=0.29, p<.001, respectively). Stone composition or fiber size had no significant correlation with energy (r=-0.05, p=0.45; r=-0.04, p=0.55) or time (r=-0.07, p=0.31; r=0.04, p=0.49). In univariate and multivariate analyses, stone volume, density, and location were significant determinants of laser energy. Stone volume remained significant for laser time in the multivariate analysis (Table 2). Median ablation efficiency and speed were 14,553 J/cm³ and 0.98 mm³/s, respectively, with no signification variation based on stone composition (p=0.52 and p=0.68).

Conclusion

During TFL-assisted ureteroscopy for stone disease, increased laser energy and time are associated with larger stone dimensions, increased density, and renal location. Stone composition and fiber size do not significantly affect cumulative laser energy or time requirements.

Funding

N/A

Lead Authors

Wilson Molina, MD
The University of Kansas Health System

Co-Authors

Willian Ito, MD
The University of Kansas Health System

Nicholas Choi, BS
University of Kansas School of Medicine

Daniel Reich, BA
University of Florida College of Medicine

Kunal Hanchate, BS
University of Florida College of Medicine

Mihaela Sardiu, PhD
The University of Kansas Health System

Holly Smith, MPH
The University of Kansas Health System

David Duchene, MD
The University of Kansas Health System

Vincent Bird, MD
University of Florida