Category: Clinical Stones: Ureteroscopy

MP29-11 - Quantitative assessment of effectiveness of ultrasonic propulsion of kidney stones

Sun, Sep 23
2:00 PM - 4:00 PM

Introduction & Objective :

Ultrasonic propulsion is an investigative technology to non-invasively reposition stones in the urinary tract.  Feasibility was shown previously in 13 awake and 2 anesthetized subjects.  Our goals for this study were to demonstrate safety and effectiveness of new exposures and transducer design and to use ureteroscopic observation to quantify the number of kidneys in which stones were repositioned. 


Methods :

Patients scheduled for ureteroscopy were recruited and consented. During surgery, ultrasonic propulsion was applied transcutaneously with the patient supine while the stone was visualized ureteroscopically.  Exposures were 350 kHz frequency, ≤ 200 W/cm2 intensity, and ≤ 3-second bursts. Ureteroscopic and ultrasound videos were recorded.  Video clips of stones receiving and not receiving propulsion bursts were scored for motion ≥ 3 mm by three endourologists blinded to the exposures. The same was done for the ultrasound (US) videos by three US experts.  The US videos were also used to measure the distance moved. Subjects were contacted weekly for three weeks to record adverse events. A 90-day chart review was conducted to collect unplanned stone-related events.


Results :

The study included 15 kidneys (10 right) in 14 subjects (10 male). Average BMI was 28.5 ± 5.2 kg/m2 and stone targets ranged from a collection of “dust” to 7 mm in size. Subjects received 16 ± 12 propulsion bursts for a total exposure time of 41 ± 39 s. All reviewers confirmed stone movements ≥ 3 mm in 14 of 15 kidneys (93%) on the ureteroscopic videos, while two reviewers reported insufficient video quality to score movement for kidney 15. The US video reviewers scored ≥ 3 mm movements in 11 of 15 kidneys (73%). This difference was likely due to out of plane motion on US. Ultrasonic repositioning obviated the need for a basket to reposition stones in 2 cases. No serious or unanticipated adverse events were observed. Non-serious events included hematuria, nausea, changes in voiding and bowel habits, and pain/discomfort, which were considered related to lithotripsy and not ultrasonic propulsion.  Skin reddening (3), skin bruising (1), and skin irritation (1) were considered related to the propulsion procedure. 


Conclusions :

Ultrasonic propulsion was shown safe and effectively repositioned stones in 93% of kidneys, despite positioning and access restrictions caused by working in an operating room on anesthetized subjects.   This first human study of these new exposures supports use in further studies to measure clinical benefits of ultrasonic propulsion in awake patients. Work supported by NIH P01 DK043881. 

Jonathan D. Harper

University of Washington
Seattle, Washington

Jessica C. Dai

University of Washington
Seattle, Washington

Helena C. Chang

University of Washington
Seattle, Washington

Barbrina Dunmire

Seattle, Washington

Bryan Cunitz

Seattle, Washington

Jeff Thiel

Seattle, Washington

Ziyue Liu

Indianapolis, Indiana

Michael Bailey

Seattle, Washington

Mathew Sorensen

Associate Professor, and Urology Residency Program Director
University of Washington School of Medicine
Seattle, Washington