URETERAL AND BLADDER LESIONS AFTER BALLISTIC, ULTRASONIC, ELECTROHYDRAULIC, OR LASER LITHOTRIPSY

Four techniques of intracorporeal lithotripsy are now available: balli stic, ultrasonic, electrohydraulic, and laser. Their therapeutic effic acies have generally been evaluated and compared, but very few data ha ve been available on their relative risks of iatrogenic trauma to the urothelial wall. We conducted a comparative analysis of this risk by t esting the pig ureteral and bladder wall with the EMS Lithoclast, Olym pus ultasonic lithotripter, Walz Lithotron EL 23, and Versa Pulse Ho:Y AG Coherent Laser. We measured the number of shockwaves or the energy required to perforate the ureter and bladder by delivering shocks perp endicular to the walls. Ureteral perforation was impossible with the 1 .0-mm Lithoclast transducer and the 1.5-mm ultrasound transducer. Perf oration was induced after 250 shocks with the 0.8-mm Lithoclast transd ucer, after 110 shocks with the 3F electrohydraulic electrode, and aft er 0.02 kJ with the laser. Bladder perforation was impossible with the 2.0-mm Lithoclast device and the 3.4-mm ultrasound transducer but was induced after 0.04 kJ had been delivered with the laser. We evaluated the iatrogenic risk under normal conditions of use by delivering the shocks tangentially to the ureteral wall and perpendicular to the blad der wall. We sacrificed animals on days 0, 1, and 6. The immediate his tologic lesions induced by the Lithoclast and the ultrasound lithotrip ter were similar, consisting of a moderate reduction of the epithelial layers or intraepithelial detachments. Electrohydraulic shocks induce d almost complete abrasion of the urothelium, and the laser induced ex tensive lesions of partial or complete necrosis of the urothelial wall . Later examination revealed similar types of histologic lesions with all of the lithotripters studied: constant abrasion of the epithelium associated with edema of the wall. In addition, parietal necrosis was observed with the laser. We conclude that the Lithoclast is as safe as the ultrasound device and safer than the electrohydraulic device and the Ho:YAG laser.