PurposeThe assessment of gallbladder function and ejection fraction using sincalide-enhanced biliary scintigraphy is a useful way to evaluate patients with recurrent right upper quadrant pain but no gallstones.Materials and MethodsWe wanted to determine whether gallbladder contraction measured by ultrasonography could be used in place of biliary scintigraphy. Biliary scans with an infusion of sincalide and concurrent ultrasonography were performed in 17 patients with histories of recurrent abdominal pain and no evidence of gallstones by ultrasound.ResultsGallbladder ejection fractions calculated by ultrasound and scintigraphy using standard techniques showed only a weak correlation. The poor performance of ultrasound appears to arise because the variable shape of the gallbladder invalidates the calculation of its volume by the formula for a prolate spheroid. When gallbladders that were ellipsoidal were subselected, correlation was improved. The level of training of the sonologist did not have a significant effect on the results.ConclusionGallbladder ejection fraction calculated by ultrasonography cannot be used routinely as a substitute for biliary scintigraphy.