Prenatal sonographic diagnosis of biliary tract malformations.

Congenital anomalies of the biliary tract include a variety of pathologic conditions, such as biliary atresia, choledochal cysts, gallbladder agenesis, congenital cholelithiasis, and gallbladder duplication. Although most of these malformations are rare and benign conditions, they may occasionally represent a major threat to extrauterine life. Visualization of a normal-sized gallbladder should be a mandatory component of the second-trimester anomaly ultrasound scan.