Placental vascular indices (VI, FI and VFI) in intrauterine growth retardation (IUGR). A pooled analysis of the literature.

Abstract

I performed a systematic review and pooled analysis to study the utility of the placental vascular flow indices vascularization index (VI), flow index (FI) and vascularization flow index (VFI) in the prediction or identification of in-utero growth restriction (IUGR). A comprehensive literature search for relevant studies was conducted using PubMed and Web of Knowledge databases. Included were cohort or case-control studies which reported (1) the statistical position and dispersion of vascular indices in a population of normal pregnancies at various trimesters of pregnancy; (2) correlation between vascular indices and gestational age; or (3) the vascular index values stratified according to the presence of SGA/IUGR versus a population of controls. Seven studies met the criteria of inclusion, for a total of 788 controls and 82 SGA cases in the first trimester, and 169 controls and 80 IUGR cases essentially enrolled in the 3rd trimester. After normalization of the means, the pooled detection rates (DRs) at a 10% false positive rate were 32.5%, 53.8% and 51.0%, respectively, for the vascular indices VI, FI and VFI in the third trimester. No significant discriminant ability was detected in the first trimester. A significant DR for IUGR was demonstrated only in the third trimester, thus limiting the utility of vascular indices to predict IUGR. VI and VFI are more reliable and yield better DR and better performance in terms of homogeneity than FI and should be evaluated in the management of third trimester IUGR and prediction of outcome.