Thulium fiber laser vs. holmium:YAG: A clinical comparison of laser lithotripsy efficiency in a retrospective of 73 patients at a tertiary stone center
Alec Mitchell1, Victor Wong1, Abdulghafour Halawani1, Ryan Paterson1, Ben Chew1.
1Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
Introduction: Since its first use by Dr. Denstedt in 1993, the holmium (Ho):YAG laser has been the gold standard laser for lithotripsy. The thulium fiber laser (TFL) is a new laser technology that has shown promising results in several preclinical studies. This new technology may expand the boundaries of laser lithotripsy. This study aimed to compare the efficacy of TFL and Ho:YAG in terms of stone fragmentation rate, operative time, and stone-free rate (SFR).
Methods: A retrospective analysis was conducted at a tertiary stone center to identify patients treated with Ho:YAG or TFL laser lithotripsy. Seventy-three cases were included: 42 patients in the Ho:YAG group and 31 in the TFL group. Operative time was calculated from scope introduction to removal. SFR was assessed with one or multiple imaging modalities; non-contrast computed tomography (CT), kidney-bladder-ureter (KUB) ultrasound, or X-ray. Other variables, including stone size, density, and prior ureteral stenting, were recorded. In the case of multiple stones, the total stone surface area was measured.
Results: Patient age (years), prior ureteral stenting, procedure time (min:sec), and total stone surface area were similar between groups. The number of treated stones was higher in the TFL group (p=0.0015). Compared to Ho:YAG, TFL showed a significantly higher rate of stone fragmentation per mm2 stone surface area (p=0.02). The data showed a similar SFR between Ho:YAG and TFL groups, as well as the size of residual fragments (<4 mm or >4mm) (Table 1).
Conclusions: This study demonstrates that the TFL has a more efficient lithotripsy effect per mm2 stone surface area than Ho:YAG. SFR was similar for both Ho:YAG and TFL; however, this is confounded by the fact that a significantly higher number of stones have been treated with TFL. In our study, TFL produced a similar SFR to Ho:YAG at a more efficient rate of lithotripsy. Further clinical studies are warranted to tease out the above results and to determine whether thulium can truly challenge holmium as the default laser in urology.
