Blood flow volume of uterine arteries in human pregnancies determined using 3D and bi-dimensional imaging, angio-Doppler, and fluid-dynamic modeling

a) 3D-angio-Doppler imaging of UtA, approximately 15 mm upstream to vessel bifurcation on the common trunk of the uterine artery at the level of the cross-over external iliac vessels. After the 3D geometry of the vessel and the spot (∅) where to measure the uterine artery was visualized the sonologist moved the probe in order to put the uterine vessel on the 2D plane where the combination of tissue imaging and angio imaging provides the best view of the spot where to measure the diameter. b) UtA diameter measured along the common UtA trunk (∅ on Fig. 1a) UtA was evidenced by angio-Doppler box and calipers were placed at the inner edges of the vessel on B-mode imaging, after partial removal of the box. c) UtA blood flow velocity measurement. After the diameter is measured, the transabdominal probe is rotated approximately 90° on the ideal fulcrum of the spot were the diameter was measured (∅) to obtain a Doppler beam angle <30 and as closest as possible to 0°.

UtA absolute flow volume (ml/min) plotted on gestational age. Original findings are reported as full dots. Best fit regression (y = 2.5589x^1.456). Upper and lower continuous lines represent the 5th, 10th, 90th, and 95th percentiles.

a) Uta flow expressed per kg fetal weight (ml/min/kg) plotted on gestational age. Best fit regression (y = 162188x^−1.8979). Upper and lower continuous lines represent the 5th, 10th, 90th, and 95th percentiles. Five longitudinal observations are plotted as individual lines. b) UtA blood flow volume ml/min/kg. Values are reported as 10th, 50th, 90th percentile.

Correlation between UtA flow volume calculated in a single artery and the PI measured in the same vessel, (Pearson r = −0.53). Black dots, data point. Continuous line, best fitting regression (y = 95.696x^−1.1438). Dashed lines 25th and the 75th percentiles.