Differentiation of benign from malignant ascites by sonographic evaluation of gallbladder wall.

The gallbladders of 65 patients with ascites were examined on ultrasonograms. In 37 patients, the thickness of the gallbladder wall was less than or equal to 3 mm and was considered normal or "single." In 28 patients, the gallbladder wall thickness was greater than or equal to 4 mm, with a central echo-free zone giving the appearance of a double wall. Of the 37 patients with single-walled gallbladders, 35 (95%) had carcinomatous peritonitis. Of the 28 patients with double-walled gallbladders, 23 (82%) had benign disease, such as liver cirrhosis (n = 22) and nephrotic syndrome with hypoalbuminemia (n = 1). The results of this study indicate that sonography is useful in determining whether the cause of ascites is malignant or benign disease.