Discrepancy between ultrasound and oral cholecystography in the assessment of gallstone dissolution

The Sunnybrook Medical Centre Gallstone Study is a randomized, controlled, double-blind study of chenodeoxycholic acid for dissolution of radiolucent gallstones. Of the first 22 patients whose stones were apparently totally dissolved on oral cholecystography, seven were found to have residual small stone fragments on ultrasound examination of the gallbladder. Continuing chenotherapy was unsuccessful in dissolving these fragments. The possibility that the residual stones represent insoluble nuclei of the original calculi must be considered. Responses to choleitholytic therapy and subsequent stone recurrences need to be reevaluated using ultrasound.