Nonimmune fetal hydrops caused by bilateral type III congenital cystic adenomatoid malformation of the lung at 17 weeks' gestation.

Type III congenital cystic malformation of the lung with nonimmune hydrops and oligohydramnios was diagnosed at 17 weeks by ultrasonography. Massive fetal cardiac compression with probable associated left- and right-sided failure causing both the oligohydramnios and the ascites, respectively, was thought to be the underlying pathophysiologic mechanism of this unusual clinical presentation. Pathologic examination after termination of the pregnancy confirmed the prenatal diagnosis.