Sonography of cholesterol in the biliary system.

The sonographic features of cholesterol within the biliary system are reviewed and a new sign is described. That cholesterol causes high reflecting echoes and may cause shadowing has been known; however, its ability to cause reverberatory artifactual echoes has not been previously appreciated. These sonographic features, while not specific, should favor the diagnosis of cholesterol stones and cholesterol polyps in the appropriate clinical situation.