64 Longitudinal study of spiral artery and intravillous blood flow and adverse pregnancy outcomes

Abstract

Superb Micovascular Imaging (SMI) improves visualization of small vessels by suppressing global motions while preserving low-flow components such as the micro-vessels in the placenta. We sought to determine if SMI aided visualization of flow velocities in spiral artery (SA) and the intravillous space (IV) can predict development of late onset fetal growth restriction (FGR), gestational hypertension (GHT) and/or preeclampsia (PE). Prospective longitudinal study measuring SA and IV flow velocity using SMI Color Doppler between 11 to 13 + 6, 18 to 21 + 6 and 28 to 34 weeks of gestation. SA and IV flow velocities were reported as resistance indices (RI). Late FGR was defined as EFW < 10th percentile after 34 weeks, and GHT and PE by ACOG standards. RI values were analyzed with multilevel modeling: individual regression curves were estimated and combined to obtain the reference intervals for SA and IV flow velocities in normal pregnancies. Student t-tests compared deviation from expected flow velocity between normal and complicated pregnancies. Of 540 pregnancies included; 19 (3.5%) had FGR, 31 (5.7%) PE and 61 (11.3%) GHT. In uncomplicated pregnancies, SA RI decreased progressively with advancing gestational age, while IV RI decreased with gestational age (Fig). Mean RI values for both SA and IV were significantly higher in the FGR group compared with uncomplicated pregnancies in the third trimester (Table). There was no significant difference in mean RI between uncomplicated pregnancies and those with PE and GHT at any gestational age. When all adverse outcomes were combined, increased SA RI was significantly associated with these outcomes only in the third trimester when compared with the control group [mean RI (SD)= 0.27(0.11) versus 0.33(0.11), respectively; p=0.042]. SMI improved the visualization of SA and IV. Significant differences were seen in pregnancies at risk mostly for late-onset FGR, but only in the early third-trimester.The potential role of SA and IV for predicting adverse outcomes appear limited. Supported by U01HD087213.View Large Image Figure ViewerDownload Hi-res image Download (PPT)