First Trimester Preeclampsia Screening: Uterine Artery Doppler Using the FMF Algorithm
Timing of Screening
According to ISUOG recommendations for preeclampsia screening, Doppler assessment of uterine arteries in the first trimester is performed between 11 weeks 0 days and 13 weeks 6 days. A second screening window has also been described at approximately 20–24 weeks. ISUOG patient materials also indicate first trimester screening between 11 and 14 weeks with repeat assessment typically at 20–24 weeks.
The rationale for early screening is that uterine artery Doppler is most informative when used to identify increased risk early enough for preventive strategies or enhanced surveillance to be meaningful. By the late third trimester, the predictive contribution of UtA-PI decreases, and other markers come to the forefront.
Components of the FMF Algorithm
Screening for preterm preeclampsia (preterm PE) using the Fetal Medicine Foundation algorithm (competing risk model) includes:
| Component | Description |
|---|---|
| Maternal factors | Maternal history and characteristics |
| MAP | Mean arterial pressure |
| UtA-PI | Uterine artery pulsatility index (Doppler) |
| PAPP-A | Pregnancy-associated plasma protein-A |
PAPP-A has been shown to demonstrate efficacy in preterm preeclampsia screening comparable to placental growth factor (PlGF) when applied in clinical practice.
Technical Aspects of Performance
During routine ultrasound examination at 11–13 weeks, gestational age is calculated using crown-rump length (CRL). MAP and UtA-PI are assessed according to established protocols. Specific threshold values of UtA-PI for risk stratification are not provided in the available fragments [to be clarified].
Algorithm Validation
The FMF competing risk model based on maternal factors and biomarkers at 11–13 weeks (O'Gorman N. et al., 2016) has undergone external validation in multiple cohorts, including studies by Mosimann B. et al. (2017) and Allen RE. et al. (2017).
Frequently asked questions
At what gestational age is uterine artery Doppler performed in the first trimester?
Between 11 weeks 0 days and 13 weeks 6 days (ISUOG); patient materials indicate a range of 11–14 weeks. A second screening window is approximately 20–24 weeks.
Which parameters are included in the FMF algorithm?
Maternal factors, mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), and PAPP-A.
Can PAPP-A be replaced with PlGF?
PAPP-A has been shown to demonstrate efficacy in preterm preeclampsia screening comparable to placental growth factor (PlGF) in clinical practice.
Why is uterine artery Doppler more important at an earlier gestational age?
By the late third trimester, the predictive contribution of UtA-PI decreases, whereas early assessment allows timely initiation of prophylaxis or enhanced surveillance.
How is gestational age calculated during screening?
Using crown-rump length (CRL) at routine ultrasound at 11–13 weeks; MAP and UtA-PI are assessed according to established protocols.