Etiology and outcome of second trimester non-immunologic fetal hydrops

This investigation was undertaken to study the conditions resulting in midtrimester fetal hydrops and to evaluate its overall prognosis as regards counseling purposes.

The etiology of midtrimester non-immune fetal hydrops was retrospectively evaluated as regards cases detected in singleton pregnancies (n=58) from January 1987 through December 1996. The condition was diagnosed by way of routine biochemical and ultrasonographic screening of a pregnant population.

The rate of diagnosed midtrimester fetal hydrops was 1 in 1700 pregnancies and the overall survival rate in this usually unexpected condition was less than 10%. Various chromosomal and fetal structural abnormalities dominated as a cause of fetal hydrops, representing 44.8% and 43.1% of the cases, respectively. Infection caused only 6.9%. The underlying etiology remained unknown in only three cases. However, in 78% the diagnosis was already known prenatally.

Although the overall prognosis is poor, knowledge of the primary etiology is important to determine a rational therapeutic strategy. If the results of routine investigations rule out malformation and abnormal chromosomes, follow-up serial ultrasonographic assessment may indicate that the hydropic state is transient, carrying a somewhat better prognosis.