Improved early prediction of pre-eclampsia by combining second-trimester maternal serum inhibin-A and uterine artery Doppler

Objective To evaluate the screening efficacy of second-trimester maternal s erum inhibin-A combined with uterine artery Doppler studies performed at 20 weeks' gestation for the prediction of pre-eclamesia. Methods Six hundred and eighty-nine consecutive unselected women who had in hibin-A levels measured between 15 and 19 weeks' gestation subsequently had color flow pulsed Doppler of both uterine arteries at the time of the anom aly scan (mean 20.5, range 18-22 weeks' gestation). The main outcome measur es were pre-eclampsia and pre-eclampsia requiring delivery before 37 weeks' gestation. The presence or absence of notches in the flow velocity wavefor m was noted, and the resistance index measured. Receiver operator curves we re created for inhibin-A and uterine artery Dopplers alone and in combinati on. Sensitivities for each method were compared at false-positive rates of 3% and 7%. Results Thirty-five women developed pre-eclampsia, of whom 15 required deli very before 37 weeks' gestation. For a false-positive rate of 7%, the sensi tivity using bilateral notches/mean resistance index greater than or equal to 0. 65 was 60% with a positive likelihood ratio of 8. 6 (confidence inter val 5.7-12.6). For the same false-positive rate, when bilateral notches/mea n resistance index greater than or equal to 0.55 and unilateral notches/mea n resistance index greater than or equal to 0.65 were combined with inhibin -A greater than or equal to 1.0 multiples of the median, the sensitivity i mproved to 71% and the positive likelihood ratio to 10.8 (confidence interv al 7.4 -15.4). For pre-eclampsia requiring delivery before 37 weeks for a f alse-positive rate of 3%, the sensitivity for bilateral notches improved fr om 27% to 60% and the positive likelihood ratio improved from 9.2 to 20.8 w hen uterine artery notch data was combined with inhibin-A. The improvement in sensitivity for the combined method compared to either inhibin-A or uter ine artery Dopplers alone, was statistically significant for both pre-eclam psia (P < 0.05) and preterm pre-eclampsia (P < 0.02). Conclusion Combination of second-trimester serum inhibin-A and uterine arte ry Doppler at 20 weeks improves the screening efficacy for the prediction o f pre-eclampsia especially when this necessitates early delivery. This comb ination might form the basis of an effective and practical early screening test for the condition.