Poster Session IV
Friday, February 7, 2020 • 3:45 PM - 5:15 PM
950: Longitudinal assessment of fetal placental arterioles and umbilical artery in normal pregnancies using novel tools

https://doi.org/10.1016/j.ajog.2019.11.961Get rights and content

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Objective

Technological limitations have hindered understanding of the physiology of fetal placental arterioles (FPA). Novel ultrasound (US) tools can now visualize and quantify microvascular flow. To our knowledge longitudinal study of FPA in pregnancy has not been done. Our objective was to determine the physiological changes in FPA across pregnancy and the response of the umbilical artery (UA) to these changes.

Study Design

Normal pregnant women with singletons were consented for serial US starting between 12 0/7 and 13 6/7 wks. US was performed every 2 wks until 16 wks, then every 4 wks until delivery. Visualization of FPA was achieved by novel microvascular color imaging on sagittal section of the placenta at the cord insertion level. Number of FPA visualized (FPA#), peak systolic velocity (FPA-PSV) and Pulsatility Index (FPA-PI) were obtained by averaging 6 measurements per US. Umbilical artery PI (UA-PI) was

Results

83 women were included in this study with 8 US per pregnancy. Nomograms were developed for FPA# and FPA-PSV (Figure 1) and FPA-PI and UA-PI (Figure 2). Cubic polynomial models represented best fit for FPA-#, PSV and PI. Linear regression represented best fit for UA-PI. FPA-# and FPA-PSV (Figure 1) increased and FPA-PI and UA-PI (Figure 2) decreased throughout gestation. The steepest decline in slope of FPA-PI was in the 3rd trimester (Figure 2). Strong positive correlation was noted between

Conclusion

In vivo evaluation of FPA is feasible. Reduced impedance of fetal placental bed is noted in early gestation and continues throughout pregnancy with an accelerated drop in the 3rd trimester. Increased FPA-PSV is driven by reduced FPA impedance along with increased fetal cardiac output. UA Doppler change in pregnancy is primarily driven by adaptation of FPA.

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