BLOOD-FLOW VELOCITIES IN HUMAN INTRAPLACENTAL ARTERIES

Objective. To characterise the physiological findings of blood circula tion in intraplacental arteries in normal and complicated pregnancies. Design. A descriptive cross-sectional study. Umbilical and intraplace ntal artery resistance index (RI) Doppler recordings during the last t rimester of pregnancy. Subjects. Forty-nine normal pregnancies and ten pregnancies complicated by fetal growth retardation. Results. RI valu es decreased from the proximal umbilical artery to the distal umbilica l artery and to intraplacental arteries. All of these vessels had decr easing RI values towards the end of pregnancy. In pathological pregnan cies an abnormal flow pattern in umbilical arteries could be associate d with either an abnormal or normal flow pattern in the intraplacental arteries. Conclusions. Blood now in intraplacental arteries can be re corded by sensitive color Doppler in normal pregnancies, but in compli cated pregnancies variation of the Doppler findings, together with ima ging difficulties of intraplacental arteries, seem to impair the appli cability of this examination as a diagnostic tool.