A Randomized Controlled Trial of Ultrasonic Propulsion-Facilitated Clearance of Residual Renal Stone Fragments vs Observation.

Purpose: In patients with residual stone fragments, ultrasonic propulsion (UP) increased the fragment passage rate by 58% and reduced risk of relapse by 70% vs untreated controls with minor associated adverse events (AEs). This study presents a second, independent trial of UP to demonstrate replication of those results and effective training of a novice team of users.

Materials and methods: This was a multicenter, prospective, open-label, randomized, controlled trial. Adults with residual fragments ≤ 5 mm seen on clinical imaging at least 4 weeks post lithotripsy were enrolled. The treatment group underwent UP; the control group did not. The effectiveness end points included the proportion of subjects reporting visual observation of stone passage within 3 weeks post procedure (treatment group) or randomization (controls) and the reduction in stone burden on follow-up imaging captured within 90 days post procedure/randomization. The safety end points were AEs within 3 weeks post procedure/randomization. The Fisher exact test was used for comparison.

Results: The trial was conducted April to October 2024. Fragments remained a median of 6 months after surgery before study enrollment. Ten of 12 treated participants passed fragments vs 2 of 12 controls (P = .003). Nine of 12 treated participants saw stone burden reduction on imaging vs 1 of 11 controls (P = .003). All AEs were mild, occurring in 7 of 12 treated participants and 4 of 12 controls.

Conclusions: Consistent with the index study, UP conducted by an independent group of operators demonstrated a higher rate of fragment passage and greater reduction in stone burden after UP compared with controls, with minor associated risk.