Combination of extracorporeal shock‐wave lithotripsy and dissolution of gallbladder stones with methyl tert‐butyl ether: A randomized study

We conducted a prospective randomized study in gallstone patients to determine whether a combination of extracorporeal shock‐wave lithotripsy and subsequent dissolution with methyl tert‐butyl ether increases the success rate of methyl tert‐butyl ether dissolution and shortens treatment time compared with monotherapy with methyl tert‐butyl ether. Fifty patients were randomized into two groups. Twenty‐five patients underwent extracorporeal shock‐wave lithotripsy before contact dissolution with methyl tert‐butyl ether, and 25 patients were treated with methyl tert‐butyl ether alone. All patients had at least three stones or stones larger than 30 mm that were radiolucent on x‐ray and had densities of less than 140 Hounsfield Units (HU) on computed tomography. Overall, the combined approach neither shortened the treatment time significantly vs. monotherapy with methyl tert‐butyl ether nor reduced the time of hospitalization. The success rate was slightly but not significantly increased compared with that of methyl tert‐butyl ether therapy alone. The recurrence rate was similar in the two groups after a median follow‐up of 1 yr. However, when subgroups of patients with at least one stone larger than 15 mm or with stones with densities of more than 60 HU were analyzed, the clearance rate after 5 mo was significantly higher (p < 0.005 and p < 0.025, respectively) in patients subjected to a combination of extracorporeal shock‐wave lithotripsy and methyl tert‐butyl ether dissolution. Extracorporeal shock‐wave lithotripsy and methyl tert‐butyl ether did not expose patients to more adverse effects than did treatment with methyl tert‐butyl ether alone. (Hepatology 1994;19:133–137).