Enhanced fragmentation of fractured gall-stones with contact lithotripsy

Abstract

SummaryGall-stone fragmentation is mainly a function of the physical characteristics of both the administered shock waves and the gall-stones. Geometrical irregularities, such as holes and cracks, have previously been shown to reduce the local stress required to break solid structures. We therefore tested the hypothesis that contact lithotripsy would fragment fractured gall-stone sooner than intact gall-stones. Fifty-four gall-stones harvested from 18 consecutive cholecystectomy patients were randomized into three groups. Group A included gall-stones which were drilled by a diamond-tipped knife creating a small crater in the stone surface. Group B were sister stones from the same gall bladder used as controls. A third stone from the same patient was used for chemical analysis. All stones were fragmented by ultrasonic contact lithotripsy using a Wolf Lithotrite at 100% power and at a frequency of 10 shock waves per s. Fragmentation time for drilled stones was 27 ± 6 s compared to 71 ± 13 s for nondrilled stones (P lt; 0.001). There was no correlation between chemical analysis and time to stone fragmentation. We conclude that fracturing of stones prior to lithotripsy reduces fragmentation time, and may thus increase the efficacy and safety of contact lithotripsy of both gall-stones and common bile duct stones.