Implementing preeclampsia screening in Switzerland (IPSISS) - first results from a multicentre registry.

Introduction The Fetal Medicine Foundation(FMF) London developed a first trimester combined screening algorithm for preterm preeclampsia(pPE) that allows a significantly higher detection of pregnancies at risk compared to conventional screening by maternal risk factors only. The aim of this trial is to validate this screening model in the Swiss population in order to implement this screening into routine first trimester ultrasound and to prescribe low dose aspirin 150mg(LDA) in patients at risk for pPE. Therefore, a multicentre registry study collecting screening and pregnancy outcome data was initiated in2020;these are the preliminary results. Methods Between June1st2020 and May31st2021 we included singleton pregnancies with pPE screening at the hospitals of Basel, Lucerne and Bern. Multiple of Medians(MoMs) of uterine artery pulsatility index(UtA-PI), mean arterial pressure(MAP), placental growth factor(PlGF) and pregnancy associated plasma protein A(PAPP-A) as well as risks were analysed as calculated by each centre's software and recalculated on the FMF online calculator for comparative reasons. Statistical analyses were performed by GraphPad Version9.1. Results During the study period 1027patients with singleton pregnancies were included. 174(16.9%) had a risk>1:100 at first trimester combined screening. Combining the background risk, MAP, UtA-PI and PlGF only, the cut-off to obtain a SPR of 11% is≥1:75. Outcomes were available for 968/1027(94.3%) patients, 951 resulted in live birth. 15(1.58%) developed classical PE, 23(2.42%) developed PE according to the ISSHP(International Society for the Study of Hypertension in Pregnancy) definition. Conclusion First trimester combined screening for PE and prevention with LDA results in a low prevalence of PE.The screening algorithm performs according to expectations, however the cut-off of>1:100 results in a SPR above the accepted range and a cut-off of≥1:75 should be considered for screening. More data are needed to evaluate, if these results are representative for the general Swiss population.