A randomized controlled trial of ultrasonic propulsion-facilitated clearance of residual renal stone fragments versus observation.

Abstract

Purpose: In patients with residual stone fragments, ultrasonic propulsion (UP) increased fragment passage rate by 58% and reduced risk of relapse by 70% vs. untreated controls with minor associated adverse events. 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 multi-center, 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 endpoints 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 endpoints were adverse events (AEs) within 3 weeks post-procedure/randomization. Fisher's Exact test was used for comparison.

Results: The trial was conducted April - 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=0.003). Nine of 12 treated participants saw stone burden reduction on imaging vs. 1 of 11 controls (P=0.003). 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 following UP compared to controls, with minor associated risk.