Journal of Ultrasound in Medicine, Vol 15, Issue 2 135-142, Copyright © 1996 by American Institute of Ultrasound in Medicine
Color Doppler sonographic assessment of placental circulation in the first trimester of normal pregnancy
L. T. Merce, M. J. Barco and S. Bau
University of Navarra, Madrid, Spain.
Our aim was to study placental circulation during the first trimester of
normal pregnancy. For this purpose, 108 single pregnancies from 4 to 15
gestational weeks were evaluated through conventional Doppler
ultrasonography. The flow velocity waveforms from the retrochorionic
arteries (spiral-radial arteries) and the umbilical artery were assessed
using the peak systolic velocity, resistive index, and pulsatility index).
Intervillous flow velocity waveform was evaluated from the maximum
velocity. The earliest color signal from the retrochorionic circulation was
registered at 4.5 weeks along with gestational sac visualization. The
venous Doppler signal from the intervillous space and the Doppler signal
from the umbilical artery were recorded with an embryo visible from the end
of week 5 onward. The retrochorionic, intervillous, and umbilical peak
systolic velocities increase, whereas the resistive and pulsatility indices
decrease progressively during early pregnancy with a significant
correlation with gestational age. Similarly, intervillous maximum velocity
gradually increases throughout the first trimester of pregnancy. Despite
some methodologic problems related to Doppler technology and the vessels
studied color Doppler sonography appears to be an adequate tool to assess
the physiologic changes in the placental circulation during early
pregnancy.