The term ''hydrops fetalis'' denotes generalized fetal edema, a condit
ion that differs from localized edema confined to head, extremities, o
r body cavities. This report illustrates a case of right-sided diaphra
gmatic hernia associated with severe edema of the head, polyhydramnios
, small hydrothorax, and ascites with an antenatal diagnosis of hydrop
s fetalis. At autopsy, edema was confined to the head and neck and the
peritoneal sac. The mechanisms responsible for these forms of localiz
ed edema were obstruction of the superior vena cava and hepatic veins,
respectively. Localized fetal edema may be confused with hydrops feta
lis. Fetal edema of the head and neck may result from obstruction of t
he superior vena cava by abnormal mediastinal structures.