UMBILICAL-CORD VENOUS PULSATION IN NORMAL FETUSES AND ITS INCIDENCE AFTER 13 WEEKS OF GESTATION

A total of 1175 umbilical venous Doppler flow velocity waveforms were acquired from 449 normal pregnant women whose fetuses were delivered at term without neonatal asphyxia or anomalies. Arterial and venous flow velocity waveforms were acquired from a free loop of the umbilical cord, The incidence of umbilical venous pulsation decreased from 30.4% at 13 similar to 14weeks of gestation to 14.8% at 21-22 weeks of gestation, After 23 weeks, this incidence was settled within 5.0 similar to 7.8%. There was no difference between the umbilical arterial resistance index of the fetuses with venous pulsation and without pulsation before 22 weeks. But the resistance index was lower in the pulsatile fetuses than in the nonpulsatile fetuses after 23 weeks of gestation, The origin of venous pulsations before early second trimester was suspected to be different from that after late second trimester.