Proposed clinical management of pregnancies after combined screening for pre-eclampsia at 30-34 weeks' gestation

Objective: To estimate the patient-specific risk of preeclampsia (PE) at 30-34 weeks’ gestation by a combination of maternal characteristics and medical history with multiple of the median (MoM) values of mean arterial pressure, uterine artery pulsatility index, serum the median (MoM) values of mean arterial pressure, uterine artery pulsatility index, serum placental growth factor and serum soluble fmsm-like tyrosine kinase-1 and stratify women into high-, intermediate- and low-risk management groups.<br /><br />Methods: This was a prospective observational study in women attending for 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’ 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, UTPI, 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 <4 weeks and delivery with PE from four weeks after assessment and up to 40 weeks’ gestation (PE 4w-40GW) was estimated.<br /><br />Results: The study population of 8,128 singleton pregnancies included 234 (2.9%) that subsequently developed PE. Using a risk cut-off for PE at <4 weeks of 1 in 50 and a risk cut-off of 1 in 150 for PE 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 at <4 weeks and 40% of those with PE at 4w-40GW. The intermediate-risk group contained a further 49% of women with PE at 4w-40GW. In the low-risk group, none of the women developed PE at <4 weeks and only 0.3% developed PE at 4w-40GW.<br /><br />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 starting from four weeks after the initial assessment and up to 40 weeks’ gestation. All pregnancies would need to be reassessed at 40 weeks’ gestation.