Factor II:C activity and uterine artery Doppler evaluation to improve the early prediction of pre-eclampsia on women with gestational hypertension

OBJECTIVE: To evaluate whether the determination of maternal plasma Factor II:C (FII:C) and mean uterine artery resistance index may be useful to early predict pre-eclampsia in patients with gestational hypertension. DESIGN: Prospective study. SETTING: Consecutive enrollment in a public tertiary clinical care centre. PATIENTS: A total of 65 women with gestational hypertension at 24-26 weeks. INTERVENTION: Measurements of maternal plasma FII:C activity levels, ultrasonographic biometrical parameters and Doppler velocimetry of maternal uterine arteries. MAIN OUTCOME MEASURE(S): The probability of developing pre-eclampsia was the main outcome of the study and it was computed by combining the FII:C and the mean uterine artery resistance index cut-off points, chosen by receiver operating characteristic (ROC) curve analysis. RESULTS: F-II:C activity levels and mean uterine artery resistance index were significantly (both P < 0.01) higher in women who developed pre-eclampsia. A weak, but significant correlation (r = 0.3, P < 0.05) was found between these two parameters. FII:C activity levels at the cut-off value of 136.5% achieved a sensitivity of 61.1% and a specificity of 71.3%, while mean uterine artery resistance index (RI) at the cut-off value of 0.57 showed a sensitivity of 85.7% and a specificity of 90.2% in predicting the onset of pre-eclampsia. When both FII:C and mean uterine RI were over the cut-off points the positive predictive value was of 89%, with a 100% negative predictive value when both were below the cut-off points. CONCLUSION: F-II:C activity levels and mean uterine artery resistance index determination at mid trimester may improve the prediction of superimposed pre-eclampsia on women with early onset gestational hypertension.