907 2D Sonographic estimation of placental weight at 20 weeks correlates with delivery placental weight

Small placentae are associated with obstetric complications. Sonographic estimated placental volume (EPV) is correlated with adverse outcomes but is not recommended in societal guidelines because proposed techniques require specialized training or equipment. We hypothesize that the Volume of a Cylinder formula using simple 2D measurements is as accurate at predicting placental weight at delivery as a previously described method. This is a prospective observational study. 2D imaging techniques were used to measure placental width, depth, height, and maximal thickness at 12, 20, and 36 weeks, and EPV was calculated using two different formulae: Volume of a Cylinder and Volume of a Shell. All patients who delivered at term and for whom placental weight at delivery was obtained were included in this analysis. Correlation between EPV and placental weight at delivery was determined using the Spearman correlation coefficient. Regression analysis was performed to determine the association between EPV with delivery placental weight. Of 148 patients enrolled in this study and who met inclusion criteria, 64 patients had measurements taken at 12 weeks, 61 patients at 20 weeks, and 53 patients at 36 weeks (Table 1). Both formulae correlated with placental weight at delivery: Cylinder correlation coefficient at 20 weeks 0.42 (p < 0.001), 36 weeks 0.31 (p<0.5), Shell correlation coefficient at 20 weeks 0.46 (p <0.001), 36 weeks 0.40 (p<0.01). In linear regression analysis, both formulae at 20 weeks were associated with placental weight at delivery, with Cylinder and Shell parameter estimates of 0.29 (p<0.01) and 0.27 (p = 0.02) respectively. There was no correlation between either volume assessment at 12 weeks with final placental weight at delivery. These data show that EPV at 20 weeks using standard 2D measurements correlate with placental weight at delivery as well as a more complex approach. Future studies are needed to determine if estimating placental weight using this approach is predictive of adverse pregnancy outcomes.View Large Image Figure ViewerDownload Hi-res image Download (PPT)