Antenatal measurement of fetal umbilical venous flow by pulsed Doppler and B-mode ultrasonography.

In this study, 163 normal fetuses of between 25 and 41 weeks' gestational age were examined sonographically using B-mode and Doppler equipment to measure umbilical vein diameter, umbilical venous flow amount (UVFA) and velocity (UVFV), and abdominal area (AA). A total number of 230 examinations were performed. The relationships between gestational age and umbilical vein diameter, UVFA, UVFV, and the UVFA/AA ratio were analyzed. Throughout pregnancy, the umbilical venous blood flow velocity remained relatively constant, whereas the umbilical venous blood flow amount increased steadily with gestational age and was proportional to abdominal area.