First-Trimester Placental Volume and Vascularization Measured by 3-Dimensional Power Doppler Sonography in Pregnancies With Low Serum Pregnancy-Associated Plasma Protein A Levels

Objective. The purpose of this study was to investigate the first‐trimester placental volume and 3‐dimensional (3D) power Doppler vascularization of pregnancies with low serum pregnancy‐associated plasma protein A (PAPP‐A) levels and to relate these findings to pregnancy outcomes. Methods. Three‐dimensional power Doppler sonography of the placenta was performed at gestational ages of 11 weeks to 13 weeks 6 days in 84 pregnancies with PAPP‐A concentrations of less than 0.4 multiple of the median (MoM). With a standardized setting, the placental volume and vascularization index (VI), flow index (FI), and vascularization‐flow index (VFI) were calculated and related to pregnancy outcomes. Results. Pregnancy outcomes were as follows: 57 pregnancies with birth weights at or above the 10th percentile (group A), 16 pregnancies with birth weights below the 10th percentile and normal Doppler findings in the umbilical artery throughout gestation (group B), and 11 pregnancies with birth weights below the 10th percentile and abnormal umbilical Doppler findings later in gestation (group C). No differences were found in PAPP‐A levels among groups. Placental volume values were significantly lower than reference limits, but no differences were found between groups. In groups A and B, there were no significant differences in 3D Doppler indices. However, these indices were significantly lower in group C (VI mean difference, −1.904; P < .001; FI mean difference, −1.939; P < .001; VFI mean difference, −1.944; P < .001). Placental vascular indices were significantly related to the severity of intrauterine growth restriction (IUGR; VI, r = 0.438; P < .001; FI, r = 0.482; P < .001; VFI, r = 0.497; P < .001) but not to the PAPP‐A MoM and placental volume values. Conclusions. Low serum maternal PAPP‐A levels are associated with altered 3D placental Doppler indices, and these changes are related to subsequent development of IUGR and adverse pregnancy outcomes.