Gallstone lithotripsy: in vitro comparison of fragmentation with a tunable-dye laser and an ultrasonic wire

Large bile duct stones require fragmentation prior to extraction through the papilla or through a percutaneous tract. This can be attempted with dissolution therapy, crushing baskets, or lithotripsy. Lithotripsy can be accomplished safely and effectively with tunable-dye laser energy delivered through a flexible, 1-F optical fiber under endoscopic or fluoroscopic guidance, but laser technology is very costly. A prototype, flexible ball-tipped wire coupled to an ultrasonic generator via a piezoelectric crystal has been developed for sonolysis of atheroma and thrombus in humans. The purpose of this experiment was to compare human gallstone fragmentation in vitro with a tunable-dye laser and this prototype wire to see if the less expensive ultrasound device might provide an alternative to costly laser technology. Gallstones from 17 patients were subjected to lithotripsy in a water bath with each device until completely fragmented or 60 seconds had elapsed. Neither device effectively fragmented cholesterol stones under these conditions. The ultrasonic wire completely fragmented 57% of bilirubinate stones in 60 seconds. The tunable-dye laser completely fragmented 100% of bilirubinate stones in less than 35 seconds (P = .04). Tunable-dye laser lithotripsy appears superior to the ultrasonic device for percutaneous treatment of bile duct stones.