Prediction of gall stone composition by ultrasound: implications for non-surgical therapy.

Oral cholecystography is the basic radiodiagnostic procedure required to assess chemical composition of gallstones as well as functional status of gall bladder prior to non-surgical management of gallstones. However, the value of ultrasound in non-surgical management of gallstones is yet to be proved. In this study we attempt to establish sonographic criteria which will predict the composition of gallstones prior to their non-surgical treatment. For this purpose the ultrasonographic characteristics of 233 patients with gallstone disease and functioning gall bladders were studied and an effort was made to correlate cholesterol and calcium content of different types of stones (as estimated by X-Ray powder diffraction study and atomic absorption spectrophotometry) with their ultrasonographic characteristics. Sonographic criteria for the presence of cholesterol stones were those which were floating and gallstones producing acoustic shadowing without internal echoes from within the stone. In detecting findings which would predict the presence of cholesterol stones on ultrasound, ultrasound had a sensitivity of 72.90% and a specificity of 100%. The predictive values of positive findings and negative findings were 100% and 93.4%, respectively. The demonstration of typical features of cholesterol stones on ultrasound obviates the need for oral cholecystography.