Sonographic classification of gallstones and outcome of extracorporeal shock wave lithotripsy

The success of extracorporeal shock wave lithotripsy (ESWL) for gallstone elimination is dependent on the lithotripter's ability to reduce the stone to fragments less than 5 mm in diameter, but wide variation in successful fragmentation rates have been reported even with the same instrument. This variation is probably due in part to differences in stone composition. Tsuchiya et al. have recently related the pre-operative ultrasound properties of gallstones to their chemical compositions. In the present study, 138 patients with cholecystolithiasis were treated with ESWL and results were evaluated in light of the pre-treatment sonogram patterns as classified by the aforementioned authors. Complete fragmentation (CF), i.e., fragments less than 5 mm, was achieved in 90% of patients with type I a patterns (pure cholesterol stones); stone number, diameter, and volume had no effects on fragmentation. Significantly lower CF rates were obtained with I b and I c (mixed cholesterol), and type II (combination) stones (p less than 0.0003). No fragmentation at all was achieved in the six stones with type III (bilirubinate) patterns. Twelve months after treatment, 45%, 25%, and 9% of the patients with type 1 a, type I b, and types I c or II (the latter two combined), respectively, were stone-free. Pure and mixed cholesterol gallstones without calcification seem to respond best to ESWL; effective treatment can be expected even when stones are numerous (4-10) or large ( greater than 35 mm). We recommend the inclusion of ultrasound properties of gallstones in the selection criteria for candidates for ESWL.