Research Partners

CIMU

Center for Industrial & Medical Ultrasound

UW Department of Urology

ITHS

Institute of Translational Health Sciences

UW CoMotion

Funding

NIH

NSBRI

UW CoMotion

Washington Research Foundation

Institute of Translational Health Sciences

W. H. Coulter Foundation

Ultrasonic Detection, Propulsion + Comminution of Kidney Stones

Current Research at the University of Washington

We report results from several clinical trials of our investigational device that is an alternative to surgery for fragmenting and facilitating clearance of small, asymptomatic renal stones. Our office-based unltrasound system images, breaks, and repositions stone fragments to facilitate their natural clearance in the urine.

We have now compiled a data base of over 200 study participants who have undergone a procedure with these investigational technologies without serious adverse events.

Ultrasonic Propulsion Clears Residual Stone Fragments

A study conducted at the University of Washington and the VA of Puget Sound demonstrates that ultrasonic propulsion of residual kidney stone fragments reduces relapse for patients who have undergone stone intervention treatments.

The investigational team reports results of a trial conducted with 82 people from 2015 to 2024. Repositioning residual fragments in the treatment group results in a 70% lower incidence of relapse — urgent medical visit or a subsequent surgery. Time to relapse was also longer by nearly 1.5 years in the treatment group.

"This study is the culmination of our work to invent ultrasonic propulsion to remove kidney stone fragments. Our treatment technology and clinical methods reduce the number of patients who return to the emergency room or their urologist with stone problems." — Mike Bailey

Randomized controlled trial of ultrasonic propulsion-facilitated clearance of residual kidney stone fragments vs. observation

Sorensen, M.D., and 16 others including B. Dunmire, J. Thiel, B.W. Cunitz, J.C. Kucewicz, and M.R. Bailey, "Randomized controlled trial of ultrasonic propulsion-facilitated clearance of residual kidney stone fragments vs. observation," J. Urol., 6, 811-820, doi:10.1097/JU.0000000000004186, 2024.

More Info

1 Dec 2024

Ultrasonic propulsion is an investigational procedure for awake patients. Our purpose was to evaluate whether ultrasonic propulsion to facilitate residual kidney stone fragment clearance reduced relapse.

This multicenter, prospective, open-label, randomized, controlled trial used single block randomization (1:1) without masking. Adults with residual fragments (individually 5 mm or smaller) were enrolled. Primary outcome was relapse as measured by stone growth, a stone-related urgent medical visit, or surgery by 5 years or study end. Secondary outcomes were fragment passage within 3 weeks and adverse events within 90 days. Cumulative incidence of relapse was estimated using the Kaplan-Meier method. Log-rank test was used to compare the treatment (ultrasonic propulsion) and control (observation) groups.

The trial was conducted from May 9, 2015, through April 6, 2024. Median follow-up (interquartile range) was 3.0 (1.8–3.2) years. The treatment group (n = 40) had longer time to relapse than the control group (n = 42; P < .003). The restricted mean time-to-relapse was 52% longer in the treatment group than in the control group (1530 ± 92 days vs 1009 ± 118 days), and the risk of relapse was lower (hazard ratio 0.30, 95% CI 0.13–0.68) with 8 of 40 and 21 of 42 participants, respectively, experiencing relapse. Omitting 3 participants not asked about passage, 24 treatment (63%) and 2 control (5%) participants passed fragments within 3 weeks of treatment. Adverse events were mild, transient, and self-resolving, and were reported in 25 treated participants (63%) and 17 controls (40%).

Human Study Combines BWL and UP Treatment

The Laboratory and University research team demonstrates that burst wave lithotripsy (BWL) followed by ultrasonic propulsion (UP) in a clinical setting clears over 70% of asymtomatic, small renal stones in awake patients. This is the first human feasibility study that uses both technologies together to clear stones.

As in preceding trials, all participants tolerated the procedure without anesthesia or medication.

Based on this successful study, the team anticipates a larger efficacy trial.

Facilitated clearance of small, asymptomatic renal stones with burst wave lithotripsy and ultrasonic propulsion

Harper, J.D., and 18 others including B. Dunmire, J. Thiel, Y.-N. Wang, S. Totten, J.C. Kucewicz, and M.R. Bailey, "Facilitated clearance of small, asymptomatic renal stones with burst wave lithotripsy and ultrasonic propulsion," J. Urol., EOR, doi:10.1097/JU.0000000000004533, 2025.

More Info

17 Mar 2025

We tested feasibility of burst wave lithotripsy (BWL) and ultrasonic propulsion to noninvasively fragment and expel small, asymptomatic renal stones in awake participants.

Adult patients suspected of having 2- to 7-mm stones were consented and screened for eligibility. BWL and ultrasonic propulsion were applied to up to 3 stones in 1 kidney of qualifying participants for a 30-minute total exposure. Participants completed a CT scan and the Wisconsin Stone Quality-of-Life (WISQOL) questionnaire within 90 days before and 120 days after the procedure. Participants were contacted weekly for 3 weeks after the procedure to assess adverse events (AEs). Outcomes included (1) no fragment > 2 mm, (2) unanticipated health care visits, (3) change in stone volume, (4) reported AEs, and (5) WISQOL score.

Forty-one participants were enrolled between April 2023 and October 2024. Twenty-one participants failed screening because no stones were seen, stones were too large or small, stone visibility was too deep or obstructed, or they declined to participate. Twenty participants with 31 stones received the research procedure with 7 undergoing a single repeat procedure. Twenty-two of 31 stones (71%) met the primary effectiveness outcome of no fragment > 2 mm, with 17 of 31 stones (55%) reported as stone free. Median stone volume reduction (IQR) was 100% (88%–100%). No participants returned unexpectedly for care related to the procedure. AEs were all Grade I by modified Clavien classification. WISQOL scores improved on 10 of 15 completed questionnaires.

Small, asymptomatic renal stones were effectively and safely removed in awake participants in a clinic setting.

Indpendent Replication of Results

Ultrasonic Propulsion Clears Residual Renal Stone Fragments

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. This study presents a second, independent trial of UP to demonstrate replication of those results and effective training of a novice team of users.

None of the UP operators in this study had previous experience with UP for the clearance of renal stone fragments. With training, they obtained similar results to the original study – Sorensen et al., above – by a team of experienced device users.

These results contributed to FDA clearance of the first UP device.

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