Extracorporeal shock wave lithotripsy of gallstones: Objectives, current limitations, and preliminary in vitro and in vivo observations

Surgical removal of gallstones is performed about 500 000 times per year in the United States. Although the usual cost ranges from $5000 to more than $10 000 per patient, the operative mortality is less than 1% for otherwise healthy persons. Nonsurgical dissolution of gallstones is often possible, but many gallstones contain calcium compounds that slow or prevent dissolution using the direct content cholesterol solvent, methyl tertbutyl ether (MTBE). Extracorporeal shock wave lithotripsy (ESL) has potential clinical utility for facilitating dissolution and possibly allowing spontaneous or induced passage of small fragments via the bile ducts and intestines. Obstacles to be overcome include predictable fragmentation of multiple stones up to 3 cm in diameter so that all particles are small enough to be rapidly dissolved or pass safely through the bile ducts (⩽ 3 mm). This must be achieved using biologically tolerable shock wave dosages without requiring general anesthesia within one or two treatment sessions. Acute and chronic safety, patient acceptance, and cost must be competitive with surgical treatment. Initial experience suggests that only solitary noncalcified stones (10% of patients with stones) have a high probability of success using ESL plus oral bile acid dissolution therapy. Improving ESL technology and direct contact fragment dissolution using MTBE should increase the clinical utility of shock wave lithotripsy of gallstones.