Value of placental volume and vascular flow indices as predictors of intrauterine growth retardation.

OBJECTIVE

To evaluate the utility of first-trimester placental volume and vascular flow indices to predict intrauterine growth retardation (IUGR).

STUDY DESIGN

In 1004 singleton pregnancies attending routine care we recorded maternal characteristics, biophysical and biochemical factors included in the first trimester screening for aneuploidy (FTSA) and uterine artery pulsatility index (PI). Placental volume, Vascularization Index, Flow Index and Vascularization Flow Index were obtained. Customized curves were used to define IUGR. We compared pregnancies with and without IUGR. The performance of different predictive models was described by the areas under the receiver operator characteristic (AUROC) curve. Predictive models of IUGR were compared using a two by two approach and subset analysis was performed.

RESULTS

Placental volume and all vascular indices were significantly lower (p<0.001, p≤0.01), and uterine artery PI higher (p<0.001), in pregnancies with IUGR, with and without associated pre-eclampsia.

RESULTS

obtained in the analysis of homogeneous subsets showed that the effectiveness of combined predictive models for IUGR improved significantly after adding vascular indices or placental volume to maternal characteristics, FTSA variables and uterine artery PI (AUROC curve value 0.703 (95% CI 0.663-0.744) versus 0.720 (95% CI 0.681-0.759) and 0.735 (95% CI 0.696-0.733), respectively). The most effective model at first trimester was that which included only maternal characteristics, uterine a-PI and placental volume, similar to that of the most complex model built with all the factors analyzed in this study AUROC curve value 0.735 (95% CI 0.696-0.773).

CONCLUSIONS

Placental volume and vascular indices were predictors factors of IUGR at first trimester. The effectiveness of combined predictive models for IUGR increased significantly after adding these factors, but the sensitivity of these models was too low for them to be considered useful in clinical practice.