Percutaneous umbilical cord blood sampling.

Percutaneous umbilical cord blood sampling is a newer, safer, and more convenient technique and can be performed in the second and third trimester of pregnancy by direct puncture of the umbilical vein near its placental insertion, using a needle guided by ultrasound. Between 2-4 ml of pure fetal blood were obtained from 10 pregnancies at between 19 and 39 weeks' gestation. This new procedure offers access to the fetal circulation for diagnosis and therapeutic purposes.