Extracorporeal shock wave lithotripsy

Abstract

Until now, radiopaque gallstones have been excluded from extracorporeal shock wave lithotripsy (ESWL), because these stones in vivo are less sensitive to the forces that cause disintegration. In Japan there is a higher percentage of patients with radiopaque gallstones than in Western countries. Our purpose in working with patients in Japan was to warrant extensive indication of ESWL to radiopaque gallstones, especially densely calcified stones. Retrospective analysis of clinical data. Patients were classified by computed tomography (CT) of stones. Group A consisted of 78 patients whose gallstones were densely calcified (CT attenuation values in Hounsfield units (HU), 473 +/- 323). Group B consisted of 22 patients whose stones had a calcified rim (CT attenuation values, 357 +/- 244). Ninety-eight patients received adjuvant dissolution therapy with ursodeoxycholic acid. Other recommendations, such as a glass of milk at night, were not given to the patients. One university hospital and one general hospital. One hundred consecutive Japanese patients with radiopaque stones in contractile gallbladder (CT attenuation values, > 150 HU, 447 +/- 310, mean +/- SD) were the subjects. With respect to the efficacy of ESWL, a degree of calcification for stones and its relationship with the rates of stone fragmentation and disappearance were assessed. Fragmentation to less than 3 mm in stone diameter was the aim, without limit of shock wave discharges and sessions. After ESWL sessions stones were fragmented successfully in 74 of the 100 patients (57 of the 78 patients in Group A, and 17 of the 22 patients in Group B). The mean number of discharges per patient was 10,435 +/- 8,726. The mean number of discharges for successful stone fragmentation of Group A (9,839 +/- 8,187) was not significantly different from that of Group B (11,376 +/- 6,344). One year after lithotripsy, 60 of the 100 patients were free of stones (45 in Group A, and 15 in Group B). It appears that patients with either densely calcified gallstones, or those in whom the stones have a calcified rim, are both suitable candidates for lithotripsy.