Trial Comparing Dual Probe Ultrasonic Lithotripsy to a Single Probe Ultrasonic Lithotripsy

Percutaneous nephrolithotomy (PNL) is used to remove large and complex stones from the upper urinary tract. Intracorporeal lithotripsy is an integral part of PNL. Commercially available intracorporeal lithotripsy modalities include ultrasonic, pneumatic, and combined ultrasonic and pneumatic models. Each modality has its inherent advantages and disadvantages. Ultrasonic lithotrites are capable of fragmenting stones while concomitantly suctioning out fragments. Unfortunately some stones are hard enough to resist fragmentation from ultrasonic lithotripsy. Pneumatic lithotrites are able to fragment all stones regardless of hardness, but this modality is unable to suction out stone pieces at the same time fragmentation is occurring. The newest lithotrite which combines both ultrasonic and pneumatic components is capable of fragmenting any stone, but also has some inherent limitations. The handpiece of the lithotripsy device is somewhat cumbersome, the suction component can clog, and the device has overheated at the maximal settings (Kuo et al). Current intracorporeal lithotrites, while functional, can certainly be improved.

Recently, a novel dual probe design has been introduced by Cybersonics of Erie, PA. This dual probe intracorporeal lithotrite is called the Cyberwand and is composed of a fixed inner probe vibrating at an ultrasonic frequency with an outer probe vibrating at about 1,000 Hz. As this new design has the potential to revolutionalize intracorporeal lithotripsy, we intend to compare this novel technology to currently available lithotripsy technology in a randomized clinical trial.

Inclusion criteria

• Patient of Methodist Urology in Indianapolis, IN
• Undergoing percutaneous nephrolithotomy for calculi greater than 2 cm
• Age 18 years or older
• Stone easily visible/measurable on kidney, ureters and bladder (KUB) or computed tomography (CT) scan preoperatively

Exclusion criteria

• Radiolucent stones
• Size of largest stone less than 2 cm
• Pregnancy
• Inability to give informed consent
• Multiple percutaneous access anticipated
• Active urinary tract infection
• Recent (within last 3 months) extracorporeal shock wave lithotripsy