Ultrasound as the initial dignostic study in patients with suspected gallstones.

The accuracy, sensitivity, and specificity of ultrasound versus oral cholecystography (OCG) in the preoperative diagnosis of gallstones was studied in 144 patients undergoing cholecystectomy. The 89 per cent accuracy of ultrasound was similar to the 92 per cent achieved with OCG. However, ultrasound was found to have a lower false-positive rate and a greater sensitivity with far fewer indeterminate studies than OCG. A high rate of nonvisualization diminished the usefulness of OCG as a first-line test. Because of a greater sensitivity less tendency for false-positive results, and a moninvasive nature, ultrasound should be the initial diagnostic study of choice in patients with suspected gallstones.