The Implementation of Preeclampsia Screening and Prevention (IMPRESS Study).

Published:November 15, 2022DOI:



      :Preeclampsia affects between 2% and 5% of pregnancies and is one of the leading causes of perinatal morbidity and mortality worldwide. Despite strong evidence that the combination of systematic preeclampsia (PE) screening based on the Fetal Medicine Foundation (FMF, London UK) preeclampsia risk calculation algorithm with treatment of high-risk patients with low dose aspirin (ASA) reduces the incidence of preterm PE more than currently used risk-factor based screening, real world implementation studies have not yet been done in Canada.


      : To assess the operational feasibility of implementing first trimester screening and prevention of preterm preeclampsia (PE) (< 37 weeks) alongside a publicly funded first trimester combined screening (FTS) program for aneuploidies.

      Study Design

      : Prospective implementation study. Consecutive pregnant patients referred for FTS (11-13+6 weeks) were offered screening for PE based on the FMF algorithm concomitantly with their aneuploidy screen. Consenting participants were screened using maternal risk factors (MF), mean arterial pressure (MAP), uterine artery Doppler pulsatility index (UTAD PI), pregnancy-associated plasma protein-A (PAPP-A) and placental growth factor (PLGF). Risk for preterm PE (< 37 weeks) was calculated using the FMF algorithm and individuals with a risk score 1/100 were recommended to use aspirin (ASA) (162 mg OD @hs, <16-36 weeks). Implementation metrics assessed included: acceptability; operational impact; proportion of aspirin (ASA) initiation; quality and safety measures; and screen performance.


      : Between Dec 1, 2020-April 23, 2021, 1124 patients consented to PE screening (98.3% uptake) and 92 (8.2%) screened positive. Appointments for patients receiving FTS aneuploidy and PE screening averaged 6 minutes longer than FTS alone, adding UTAD PI averaged 2 minutes. Of 92 patients who screened high-risk for PE, 72 (78.3%) were successfully contacted prior to 16 week's gestation. Of these, 62 (86.1%) initiated aspirin, 10 (13.9%) did not. Performance audit identified a consistent negative bias with MAP measurements (median MOM 10% below 1): other variables were satisfactory. There were seven cases of preterm preeclampsia (0.69%); 5 and 2 in the high and low risk groups respectively. Screening detected 5/7 (71.4 %) of preterm preeclampsia cases, with improved performance after adjustment for ASA treatment effect.


      : This study confirms the operational feasibility of implementing an evidence-based PE screening and prevention program in a publicly funded Canadian setting. This will facilitate implementation into clinical service and the scaling up of this program at a regional and provincial level.


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