A 24-YEAR-OLD woman who was pregnant with her first child underwent routine ultrasonography at 34 weeks of gestation. She had a history of primary epilepsy, which was treated during her pregnancy with valproic acid. No seizures had occurred during the pregnancy. Ultrasonography showed a cystic lesion in the right upper quadrant of the abdomen of the fetus (Figure 1). The fetus (including the right kidney) was normal in all other respects. At 36 weeks of gestation, a second ultrasound confirmed the cystic lesion in the right upper quadrant of the fetus.
Labor was spontaneous at 36 weeks of gestation, and a girl was born weighing 2.87 kg. The Apgar score at 1 and 5 minutes was 10. The results of a physical examination of the neonate confirmed the presence of a right hypochondrial mass. The neonate's first few days were uneventful. Jaundice did not develop in the neonate (ie, the