Four techniques of intracorporeal lithotripsy are now available: ballistic, ultrasonic, electrohydraulic, and laser. Their therapeutic efficacies have generally been evaluated and compared, but very few data have been available on their relative risks of iatrogenic trauma to the urothelial wall. We conducted a comparative analysis of this risk by testing the pig ureteral and bladder wall with the EMS Lithoclast, Olympus ultrasonic lithotripter, Walz Lithotron EL 23, and Versa Pulse Ho:YAG Coherent Laser. We measured the number of shockwaves or the energy required to perforate the ureter and bladder by delivering shocks perpendicular to the walls. Ureteral perforation was impossible with the 1.0-mm Lithoclast transducer and the 1.5-mm ultrasound transducer. Perforation was induced after 250 shocks with the 0.8-mm Lithoclast transducer, after 110 shocks with the 3F electrohydraulic electrode, and after 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 bladder wall. We sacrificed animals on days 0, 1, and 6. The immediate histologic lesions induced by the Lithoclast and the ultrasound lithotripter were similar, consisting of a moderate reduction of the epithelial layers or intraepithelial detachments. Electrohydraulic shocks induced almost complete abrasion of the urothelium, and the laser induced extensive lesions of partial or complete necrosis of the urothelial wall.(ABSTRACT TRUNCATED AT 250 WORDS)