Purpose: to determine the best Doppler flow velocimetry index to predict small infants for gestational age (SGAI), in pregnant women with hypertensive syndromes.
Methods: a cross-sectional study was conducted enrolling 129 women with high blood pressure, submitted to doppler velocimetry up to 15 days before delivery. Women with multiple fetuses, fetal malformations, genital bleeding, placental abruption, premature rupture of fetal membranes, smoking, use of illicit drugs, and chronic diseases were excluded. A receiver operating characteristic (ROC) curve for each Doppler variable was constructed to diagnose SGAI and the sensitivity (Se), specificity (Sp), positive (PLR) and negative (NLR) likelihood ratio were calculated.
Results: the area under the ROC curve for the middle cerebral artery resistance index was 52% (p=0.79) with Se, Sp, PLR, and NLR of 25.0, 89.1, 2.3 and 0.84% for a resistance index lower than 0.70, respectively. While the area under the ROC curve for the resistance index of the umbilical artery was 74% (p=0.0001), with Se=50.0%, Sp=90.0%, PLR=5.0 and NLR=0.56, for a resistance index higher or equal to 0.70. The area under the ROC curve for the resistance index umbilical artery/middle cerebral artery ratio was 75% (p=0.0001). When it was higher than 0.86, the Se, Sp, PLR and NLR were 70.8, 80.0, 3.4 and 0.36%, respectively. For the resistance index of the middle cerebral artery/uterine artery ratio, the area under the ROC curve was 71% (p=0.0001). We found a Se=52.2%, Sp=85.9%, PLR=3.7 and NLR=0.56, when the ratio was lower than 1.05. When we compared the area under the ROC curve of the four doppler velocimetry indexes, we observed that only the resistance index umbilical artery/middle cerebral artery, resistance index middle cerebral artery/uterine artery and resistance index umbilical artery ratios seem to be useful for the prediction of SGA.
Conclusion: in patients with high blood pressure during pregnancy, all doppler velocimetry parameters, except the middle cerebral artery resistance index, can be used to predict SGAI. The umbilical artery/middle cerebral artery ratio seems to be the most recommended one.