Proposed clinical management of pregnancies after combined screening for pre‐eclampsia at 19–24 weeks' gestation

ABSTRACT Objective To estimate the patient‐specific risk of pre‐eclampsia (PE) at 19–24 weeks' gestation by a combination of maternal characteristics and medical history with multiples of the median (MoM) values of mean arterial pressure (MAP), uterine artery pulsatility index (UtA‐PI), serum placental growth factor (PlGF) and serum soluble fms‐like tyrosine kinase‐1 (sFlt‐1), and stratify women into high‐, intermediate‐ and low‐risk management groups. Methods This was a prospective observational study in women attending a second‐trimester ultrasound scan at 19–24 weeks as part of routine pregnancy care. Patient‐specific risks of delivery with PE < 32 weeks and < 36 weeks' gestation were calculated using the competing‐risks model to combine the prior risk from maternal characteristics and medical history with MoM values of MAP, UtA‐PI, PlGF and sFlt‐1. On the basis of these risks, the population was stratified into high‐, intermediate‐ and low‐risk groups. Different risk cut‐offs were used to vary the proportion of the population stratified into each risk category and the performance of screening for delivery with PE at < 32 weeks' gestation, at 32–35 weeks and at ≥ 36 weeks was estimated. In addition to empirical performance, we also derived model‐based performance because the number of cases of PE delivering < 32 weeks was low. Results The study population of 7748 singleton pregnancies included 268 (3.5%) that subsequently developed PE. Using a risk cut‐off of 1 in 100 for PE delivering < 32 weeks' gestation and a risk cut‐off of 1 in 300 for PE delivering < 36 weeks, the proportion of the population stratified into high‐, intermediate‐ and low‐risk was 0.9%, 17.2% and 81.9%, respectively. The high‐risk group contained 97% of pregnancies with PE < 32 weeks and 45% of those with PE at 32–35 weeks. The intermediate‐risk group contained a further 46% of women with PE at 32–35 weeks. The low‐risk group contained only 0.03% of pregnancies with PE < 32 weeks and 9% of those with PE at 32–35 weeks. Conclusion Risk stratification of PE by the combined test at 19–24 weeks' gestation can identify, first, a group which constitutes < 1% of the total population and contains > 95% of those that will develop PE < 32 weeks and are in need of intensive monitoring at 24–31 weeks and, second, a group which constitutes < 20% of the total and contains > 90% of those that will develop PE at 32–35 weeks and are in need of reassessment at 32 weeks. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.