EP16.17: Measurement of placental bed vascularisation during first trimester by using microvascular flow ultrasound imaging in normal pregnancies

To assess the reproducibility of microvascular flow (MV-Flow) imaging for the microvascular architecture in the placental bed and evaluate the correlation between vascular index (VI) in different segments of placenta and uterine artery during first trimester in normal pregnancy. This prospective study evaluated the placental microvascular at 11 weeks to 13 weeks 6 days in women with singleton pregnancies. A quantification techniques using MV-Flow ultrasound imaging was performed to assess the placental blood flow. VI was acquired in different segments of placenta and different placental location. Moreover, the fetal Crown–rump length, the thickness of the placenta and the uterine artery Doppler indices were examined. Intraclass correlation coefficients (ICC) and Bland-Altman analysis were used to assess intra- and interobserver variability. In total, 106 women with singleton pregnancies were included in this study. The intraobserver ICC for the VI in upper, middle, and lower segments of the placenta were 0.755, 0.844 and 0.828, respectively. The interobserver ICC were 0.781, 0.807 and 0.797 for the VI in upper, middle, and lower segments of the placenta, respectively. During the first trimester, the 5th through 95th percentile values of normal VI in upper, middle, and lower segments of the placenta were ranged from 13.1 to 67.7, 14.3 to 66.2, 12.0 to 62.1. There was no significant difference in the VI values in upper, middle, and lower segments of the placenta between anterior and other position of placenta. Regression analysis showed that the VI in middle segments of the placenta was affected by the uterine artery. MV-Flow imaging provides a new informative tool to explore the placental microvascular perfusion at first trimester. The VI is an optimal parameter to quantify the placental vascularity and reduces with increasing uterine artery pulsatility index and resistance index.