Uterine artery Doppler screening for pre-eclampsia: comparison of the lower, mean and higher first-trimester pulsatility indices.

OBJECTIVES

A previous study suggested that the lower uterine artery pulsatility index (PI) is a better predictor of pre-eclampsia than is either the mean or higher indices. The aim of this study was to assess the relative value of these three indices for the prediction of pre-eclampsia in the first trimester of pregnancy.

METHODS

This was a prospective study of 6221 singleton pregnancies. Uterine artery PI was obtained at the time of the 11-14-week nuchal translucency scan and receiver-operating characteristics curves for the lower, mean and higher PI value of the two uterine arteries in the prediction of pre-eclampsia were calculated.

RESULTS

There were 178 cases of pre-eclampsia. The associations between uterine artery PI and pre-eclampsia were stronger for early (requiring delivery < 34 weeks' gestation) and preterm (requiring delivery < 37 weeks) pre-eclampsia compared to pre-eclampsia at any gestation. There was no significant difference in the strength of the association between lower, mean and higher PI for pre-eclampsia at any gestation.

CONCLUSIONS

First-trimester uterine artery PI is strongly associated with the development of early and preterm pre-eclampsia. Lower, mean and higher uterine artery PIs are comparable in screening for pre-eclampsia. Any differences that exist between the lower, mean and higher uterine artery indices are unlikely to have a significant impact on screening sensitivities.