Evaluating Burst Wave Lithotripsy and Ultrasonic Propulsion for Small Asymptomatic Renal Stones

The feasibility of utilizing burst wave lithotripsy (BWL) and ultrasonic propulsion for the noninvasive fragmentation and expulsion of small, asymptomatic renal stones in awake patients is currently under investigation. A previous randomized control trial highlighted that the removal of secondary small, asymptomatic renal stones during surgical procedures for primary stones significantly reduced the likelihood of relapse by 82% (Sorensen et al., NEJM, 2022;387:506-13). The primary aim of this study was to assess the effectiveness of BWL and ultrasonic propulsion in treating small asymptomatic stones in a clinic-based setting without the need for anesthesia. Participants who had up to three stones, measuring between 2-7 mm in diameter, were identified through computerized tomography (CT) scans performed within the last 90 days. Candidates were screened to ensure the stones could be targeted with the ultrasound device, excluding those with untreated infections or who could not temporarily discontinue anticoagulants. The participants underwent transcutaneous ultrasound imaging, followed by BWL therapy for stone fragmentation and ultrasonic propulsion to aid in repositioning stone fragments. The treatment lasted 30 minutes, with participants continuously monitored for cardiac health. Pain levels were assessed before and after the procedure, and postoperative urine samples were evaluated using a hematuria scoring system. Participants were monitored weekly for three weeks to assess for any adverse events (AEs) and fragment passage. Out of thirteen enrolled participants, nine underwent the procedure, with successful follow-up CTs showing that two individuals were stone-free. On average, the procedure resulted in a 70% reduction in stone volume. Mild and self-resolving AEs, including hematuria and renal colic, were recorded. Overall, the study indicates that it is indeed feasible to noninvasively eliminate small, asymptomatic renal stones in awake individuals, presenting a promising alternative that could prevent the need for emergency interventions or surgical procedures in the future.