Proposed clinical management of pregnancies after combined screening for preeclampsia at 30-34 weeks’ gestation : Third trimester screening for preeclampsia

Objective To estimate the patient-specific risk of pre-eclampsia (PE) at 30–34 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-, intermediateand low-risk management groups. Methods This was a prospective observational study in women attending a third-trimester ultrasound scan at 30–34 weeks as part of routine pregnancy care. Patient-specific risks of delivery with PE at< 4 weeks from assessment and at< 40 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-, intermediateand 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< 4 weeks from assessment and delivery with PE from 4 weeks after assessment and up to 40 weeks’ gestation was estimated. Results The study population of 8128 singleton pregnancies included 234 (2.9%) that subsequently developed PE. Using a risk cut-off of 1 in 50 for PE delivering at< 4 weeks and a risk cut-off of 1 in 150 for PE delivering at< 40 weeks’ gestation, the proportion of the population stratified into high, intermediate and low risk was about 3%, 26% and 71%, respectively. The high-risk group contained 90% of pregnancies with PE at< 4 weeks and 40% of those with PE at 4 weeks from assessment to 40 weeks’ gestation. The intermediate-risk group contained Correspondence to: Prof. K. H. Nicolaides, Fetal Medicine Research Institute, King’s College Hospital, 16–20 Windsor Walk, Denmark Hill, London SE5 8BB, UK (e-mail: [email protected]) Accepted: 15 September 2016 a further 49% of women with PE at 4 weeks from assessment to 40 gestational weeks. In the low-risk group, none of the women developed PE at< 4 weeks and only 0.3% developed PE at 4 weeks to 40 gestational weeks. Conclusion The study presents risk stratification of PE by the combined test at 30–34 weeks, aiming to identify a high-risk group in need of intensive monitoring from the time of the initial assessment and up to 40 weeks’ gestation and an intermediate-risk group in need of monitoring from 4 weeks after the initial assessment and up to 40 weeks’ gestation. All pregnancies would need to be reassessed at 40 weeks’ gestation. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.