Blood flow velocities in human intraplacental arteries

Objective. To characterise the physiological findings of blood circulation in intraplacental arteries in normal and complicated pregnancies.Design. A descriptive cross-sectional study. Umbilical and intraplacental artery resistance index (RI) Doppler recordings during the last trimester of pregnancy.Subjects. Forty-nine normal pregnancies and ten pregnancies complicated by fetal growth retardation.Results. RI values decreased from the proximal umbilical artery to the distal umbilical artery and to intraplacental arteries. All of these vessels had decreasing RI values towards the end of pregnancy. In pathological pregnancies an abnormal flow pattern in umbilical arteries could be associated with either an abnormal or normal flow pattern in the intraplacental arteries.Conclusions. Blood flow in intraplacental arteries can be recorded by sensitive color Doppler in normal pregnancies, but in complicated pregnancies variation of the Doppler findings, together with imaging difficulties of intraplacental arterie...