Antenatal three-dimensional sonographic features of fetal biliary atresia.

We present antenatal three-dimensional (3D) sonographic features of fetal biliary atresia. A 38-year-old pregnant Japanese woman was referred to our ultrasound clinic because of a fetal intra-abdominal cyst at 19 weeks of gestation. Conventional two-dimensional (2D) sonography and 3D sonography with an inversion mode showed a round cyst with a tiny dip in the subhepatic area. At 34 weeks, conventional 2D sonography and 3D sonography with inversion and transparent X-ray modes clearly revealed a round to oval cyst connected with the gallbladder via the cystic duct. A diagnosis of choledochal cyst (type I) was suggested antenatally. However, the final diagnosis made by employing operative cholangiography during surgery was biliary atresia (type I cyst) at 25 days of life. To the best of our knowledge, this is the first report of biliary atresia employing antenatal 3D sonography with inversion and transparent X-ray modes.