AUA 2018: Holmium Laser Lithotripsy for Ureteral and Renal Stones: Is Dusting Equivalent to Fragmenting?

San Francisco, CA USA ( Dr. Thomas Knoll, from University of Tuebingen, presented research comparing two commonly used holmium laser lithotripsy settings for ureteroscopic stone treatment. The variables of frequency, energy, pulse length and shape impact the laser’s effect on the stone and therefore the outcomes of dusting and fragmentation. As ureteroscopy has become the primary treatment of choice for upper tract stones, this prospective study of 177 patients aimed to determine the optimum laser settings to improve stone management.

Patients with solitary ureteral or renal stones were treated using rigid or flexible ureteroscopes under fluoroscopic control. A low power holmium laser and 275µm ball tip laser fibers were utilized during all stone disintegration. The dusting settings implemented ranged from 0.4 to 0.6 joules and 18 to 20 hertz, whereas fragmentation settings ranged from 1.2 to 1.8 joules and 8 to 12 hertz depending on the surgeon’s preference. The decision to fragment or dust was also at the surgeon’s discretion. Patients were treated for UTIs prior to the procedure and received antibiotic prophylaxis.

Data reveals comparable stone sizes, pre-stenting rates, intraoperative and postoperative complications. 116 renal stones and 61 ureteral stones were operated on. Fragmentation settings were selected for 49 renal stones and 43 ureteral stones while dusting settings were utilized for 67 renal stones and 18 ureteral stones. Although operating room (OR) time was comparable, laser duration differed drastically. Laser time under dusting settings lasted 456 seconds compared to 63 seconds spent during fragmentation. Dusting settings also obstructed intraoperative vision in 46% of patients compared to 27% of patients undergoing fragmentation. All 177 patients but one were fluoroscopically stone free using either setting. Stone free rates of 91.8% and 34% were measured using post-operative abdominal x-ray for fragmenting and dusting, respectively.

In conclusion, although both methods of lithotripsy are proven to be viable options to treat upper tract stones, fragmentation settings are recommended when possible. As dusting has such a low stone-free rate, follow-up is typically necessary. Therefore, Dr. Knoll and his team suggest that dusting settings are withheld for cases when anatomy complicates stone extraction or if the stone burden is substantial.

Presented by: Thomas Knoll, MD

Written by: Ruchita Patel, Department of Urology, University of California-Irvine at the 2018 AUA Annual Meeting - May 18 - 21, 2018 – San Francisco, CA USA