Percutaneous fetal umbilical blood sampling: procedure safety and normal fetal hematologic indices.

Percutaneous umbilical blood sampling allows direct access to the fetal circulation. We describe our experience with the procedure in the first 100 patients whose fetuses were at risk for hemolytic anemia, chromosomal abnormalities, coagulopathy, or intrauterine infection. Hematologic indices, including hemoglobin, hematocrit, red blood cell count, white blood cell count, and platelet count, were analyzed from 50 of the fetuses who were normal at delivery. Normal values and gestational age regression curves (from 17 to 37 weeks' gestation) are presented. The technique and complications of the procedure are described. Percutaneous umbilical blood sampling affords useful information in prenatal diagnosis and entails a low rate of complications.