Extracorporeal shock-wave lithotripsy and methyl tert-butyl ether for partially calcified gallstones

To explore the possibility that gallbladder stone fragments might be able to be safely dissolved using methyl tert-butyl ether immediately after extracorporeal shock-wave lithotripsy (ESWL), a feasibility study in 8 patients with one to four partially calcified gallbladder stones was performed. The gallstones averaged 2.2 cm in diameter (range 1.3-3 cm) and contained layered or diffuse calcium detectable by computed tomography scan only (7 patients) or plain film (1 patient). After a 5F (1.7 mm) pigtail catheter was placed percutaneously into the gallbladder, ESWL fragmentation was performed using a renal stone lithotriptor. The patients were under general anesthesia and in the prone position on a support gantry designed for gallbladder stone ESWL. Following ESWL, methyl tert-butyl ether was infused and aspirated via the gallbladder catheter until no further stone material was radiologically detectable or could be dissolved. After 8-26 h (mean = 13 h) of methyl tert-butyl ether therapy, no radiologically detectable gallstones remained in 6 of 8 patients. Shell fragments of three peripherally calcified stones in 1 patient and the densely calcified, predominantly pigment stone in a second patient were refractory to combined therapy. Both ESWL and treatment with methyl tert-butyl ether were well tolerated in all patients, although bile leakage after catheter removal occurred in 3 patients, one of whom was treated by cholecystectomy. Additional measures to prevent bile leakage may be advisable if these two modalities are to be used in tandem. We found no evidence, however, that predissolution stone fragmentation with ESWL predisposed the gallbladder to either mucosal damage by methyl tert-butyl ether or increased absorption of it.