Ideal Timing for Preeclampsia Screening Using Uterine Artery Doppler Velocimetry
For high-risk women, perform uterine artery Doppler screening at 18-24 weeks' gestation (specifically at 20-24 weeks alongside the routine fetal anomaly scan), and do not repeat it later in the second trimester as this provides limited additional value. 1
Risk-Based Screening Approach
First Trimester (11-14 weeks)
- Uterine artery Doppler can be incorporated into first-trimester screening algorithms when combined with maternal risk factors, blood pressure, and placental growth factor 2
- However, first-trimester uterine artery Doppler alone has insufficient predictive ability to be clinically useful as a standalone screening test 1, 3
- The ISSHP supports first-trimester screening when integrated into local health systems, though cost-effectiveness remains unestablished 2
Second Trimester (18-24 weeks) - OPTIMAL TIMING
This is the most clinically useful window for uterine artery Doppler screening in high-risk populations:
- Perform at 18+0 to 24+6 weeks (ideally 20-24 weeks) alongside the routine fetal anomaly scan 1
- At this timing, uterine artery Doppler combined with maternal factors and fetal biometry can detect 89% of very preterm SGA below the 5th centile with a 10% false positive rate 1
- Mean uterine artery pulsatility index (PI) ≥95th centile is the recommended measurement parameter 1
Clinical Decision Algorithm Based on Second Trimester Results:
If mean uterine artery PI is NORMAL (≤95th centile):
- Risk of placental dysfunction, hypertensive disorders, and early-onset FGR is low 1
- Commence serial fetal biometry scanning in the third trimester starting at 32 weeks 1
If mean uterine artery PI is ABNORMAL (>95th centile):
- Commence serial scanning earlier at 24+0 to 28+6 weeks, determined individually 1
- Do NOT repeat uterine artery Doppler later in the second trimester - this provides limited additional value even though some abnormal results may normalize 1
Why Not Other Timings?
Third Trimester
- Third-trimester uterine artery Doppler is NOT an effective risk assessment tool in unselected pregnancies 1
- It has moderate utility only when FGR is already suspected, but not as a standalone screening test 1
Low-Risk Populations
- Uterine artery Doppler screening is NOT recommended for routine use in low-risk women 3
- A recent publication specifically did not support second-trimester maternal uterine artery evaluation as a screening tool in low-risk women 3
- The ACR Appropriateness Criteria found no trials supporting its use as an FGR screening tool in low-risk populations 3
Key Clinical Pitfalls to Avoid
Don't screen low-risk women - The evidence consistently shows poor sensitivity and lack of clinical utility in unselected populations 3, 4
Don't repeat Doppler in late second trimester - While some abnormal results normalize, repeating at 28+ weeks adds limited value and those with normalization still carry increased risk 1
Don't use uterine artery Doppler as the sole screening method - It should be combined with maternal risk factors, blood pressure measurements, and biomarkers for optimal prediction 2, 1
Recognize the primary benefit - Much of the utility of uterine artery Doppler screening for FGR comes from identifying women at risk for early-onset preeclampsia rather than FGR itself 1
Supporting Evidence Quality
The most recent and highest-quality evidence comes from the 2024 BJOG Green-Top Guideline 1, which provides Grade B recommendations based on Level 2++ evidence. This is supported by the 2018 ISSHP guidelines 2 and multiple international consensus statements 5. Recent research from 2025 6 confirms that performance at 18-22 weeks in high-risk pregnancies is excellent for predicting early-onset preeclampsia and early-onset SGA with NPV >97%.