Gray-scale ultrasonography as a screening procedure in the detection of gallbladder disease.

The sonographic and surgical findings in 180 patients who underwent cholecystectomy for gallbladder disease were reviewed and correlated. Four abnormal groups were established. In Group I, the gallbladder was visible and contained structures which cast an acoustic shadow. In Group II, there was constant shadowing in the region of the gallbladder fossa, but the gallbladder itself was not visible. In Group III, there was a constant, immobile, echo-dense, nonshadowing area in the gallbladder wall. In Group IV, nonshadowing echoes were seen within the gallbladder lumen. The overall accuracy of ultrasound was 98.9%; the false-negative rate was 2.2%, the false-positive rate 2.8%. 5.6% of Group I patients had normal oral cholecystograms. Because of its high accuracy, minimal preparation, speed of diagnosis, and cost-effectiveness, the authors recommend that ultrasonic cholecystography be considered as a screening method, particularly for small polyps (< 4 mm).