Fetal liver ultrasound measurements in isoimmunized pregnancies.

Sixteen isoimmunized pregnancies at risk for erythroblastosis fetalis were managed by serial amniocenteses for bilirubin delta optical density at 450 nm (delta OD450). Before amniocentesis each fetus was evaluated ultrasonically and the fetal liver size, the abdominal circumference, and the umbilical vein diameter, in both the fetal liver and the umbilical cord, were measured. The ultrasonically determined fetal liver size, as well as its growth rate, was found to be greater than normal during the last two weeks before intervention (intrauterine transfusion or delivery) in all eight fetuses with severe hemolytic disease. The umbilical vein diameter in the fetal liver was above normal in only one fetus, whereas the abdominal circumference was increased in only three of the eight severely affected fetuses. These data suggest that serial fetal liver ultrasound measurements may be useful as an adjunct to amniotic fluid analysis to predict the severely affected fetus in need of prompt intervention (intrauterine transfusion or delivery).