Non-immune hydrops fetalis: rapidity of onset and usefulness of prenatal ultrasonography.

Non-immune hydrops fetalis (NIHF) has become more common than immune hydrops fetalis as a cause of fetal hydrops and its contribution to the total perinatal mortality rate has increased from 0.1% to 3.0% for the 10 years to 1979. A case is reported where an antenatal ultrasonograph performed within 24 hours of delivery showed hydrops was not present, however, at birth the infant was grossly hydropic and died despite intensive management. This case shows the rapidity of onset of NIHF and the devastating effect of this disorder. A review of two large series of NIHF revealed that in only 11.4% and 16.3% respectively, a significant uncorrectible associated major malformation may have been missed by antenatal ultrasonography. Hence, if prenatal ultrasonography fails to reveal a major malformation a viable fetus with NIHF should be regarded as salvageable. Pulmonary hypoplasia occurred in over 90% and is probably due to compression from serous cavity effusions. Thus to improve survival the ultrasonographer needs to watch for the development of serous cavity effusions so that a pregnancy complicated by NIHF can be terminated before the fetus develops pulmonary hypoplasia.