Fetal umbilical venous flow measured in utero by pulsed Doppler and B-mode ultrasound. I. Normal pregnancies.
Umbilical venous blood flow was measured with a pulsed Doppler unit, which was used in combination with a B-mode ultrasonic imaging system to permit location of the umbilical vein and measurement of its cross-sectional area. The accuracy and limitations of the method are discussed. Forty-seven normal fetuses with gestational ages ranging from 22 weeks to term were studied on a total of 61 occasions. Flow increased with gestational age until 36 weeks, was maximal between 37 and 38 weeks, then decreased during the last 2 weeks of pregnancy. Flow per unit of fetal weight was constant during pregnancy until 36 to 37 weeks, when a reduction occurred.
D001783:Blood Flow Velocity; D005260:Female; D005333:Fetus / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D008722:Methods; D011247:Pregnancy; D014463:Ultrasonography; D014471:Umbilical Veins / Q000196:embryology*