The benefit of removing small residual kidney stone fragments after surgery has been debated, as current U.S. urology guidelines suggest post-surgical imaging to detect any leftover fragments and advise secondary endoscopic procedures for removal. Residual fragments are linked to higher relapse rates, often requiring further clinical interventions. This study examined the effectiveness of a noninvasive, ultrasound-based technology for fragment removal in reducing relapse rates. In a multicenter, randomized, controlled trial, 82 adults with residual kidney stone fragments of 5 mm or smaller were divided into two groups: one receiving the ultrasound-guided procedure for fragment clearance and the other undergoing observation only (ClinicalTrials.gov number, NCT02028559). The primary outcome was the rate of relapse, defined by future symptomatic or unscheduled medical visits, need for additional surgeries, or increased stone size observed through annual CT exams.
After an average follow-up of 2.4 years, results showed a 68% reduction in relapse rates for the treatment group compared to controls, with an absolute difference of 20% versus 48%. Time-to-relapse was also significantly longer in the treatment group, averaging 1505 days compared to 995 days in the control group. Asymptomatic passage of fragments within the first three weeks was significantly higher in the treatment group, with 63% of patients passing fragments compared to only 5% in the control group. The average number of treatment sessions was 1.35, and mild adverse effects, such as transient bruising or discomfort, were reported in only a few cases. This study suggests that noninvasive ultrasound-assisted fragment removal can effectively reduce relapse rates, with minimal associated risk.
