Burst wave lithotripsy (BWL) may enable urologists to fragment kidney stones noninvasively in their offices, according to the findings of the first feasibility study of the technique in patients.

BWL delivers transcutaneous, cyclic, low pressure ultrasound pulses (rather than shock waves) from a handheld transducer to fragment stones.

In the study (Clinicaltrials.gov identifier: NCT03873259), investigators tested BWL at a frequency of 390 kHz in 19 patients who had 23 urinary stones sized 12 mm or less. Mean stone size was 5.7 mm. BWL was applied for up to 10 minutes under anesthesia.


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Of the 23 stones, 21 stones (91%) were fragmented. A median of 90% of stone volume was completely comminuted (broken into fragments of 2 mm or less),, Jonathan D. Harper, MD, of the University of Washington in Seattle, and colleagues reported in The Journal of Urology. Complete fragmentation occurred in 9 of 23 stones (39%).

The investigators noted that existing shock wave lithotripsy procedures, by comparison, fragment approximately 60% of stones to under 4 mm fragments within an hour.

The investigators had difficulty fragmenting 7 stones. They speculated that stones larger than the BWL beam width or smaller than the BWL wavelength were less responsive to BWL. Air bubbles from the ureteroscopy was another impediment. 

Using ureteroscopy video, an independent kidney tissue anatomist blinded to the exposure evaluated tissue injury after BWL and found only mild reddening and bleeding on the papilla. No other adverse events were reported.

According to Dr Harper’s team, the promising results of this BWL study are “a step toward an office-based lithotripsy for awake patients.”

Disclosure: Sonomotion supplied the BWL technology. Please see the original reference for a full list of disclosures.

Reference

Harper JD, Lingeman JE, Sweet RM, et al. Fragmentation of stones by burst wave lithotripsy in the first 19 humans. J Urol. Published online March 21, 2022. 207(5):1067-1076. doi:10.1097/JU.0000000000002446