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Poster Session 3

(925) A New Reference for Umbilical Artery Doppler in the Second and Third Trimesters

Friday, January 31, 2025
10:30 AM – 12:30 PM  

    Submitting Author and Presenting Author(s)

  • Sophia Rahimi, BSc, MSc

    Temerty Faculty of Medicine, University of Toronto
    Toronto, Oregon, Canada

    • Coauthor(s)

  • JK

    John C. Kingdom, MD

    Dept OBGYN Mount Sinai Hospital University of Toronto
    Toronto, Ontario, Canada

  • AV

    Arietta Vayenas

    Research Student
    Sunnybrook Research Institute, Sunnybrook Health Sciences Centre
    Toronto, Canada

  • VS

    Vasilica Stratulat

    Mount Sinai Hospital
    Toronto, Ontario, Canada

  • NM

    Nir Melamed, MD

    Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Sunnybrook Health Sciences Centre
    Toronto, Ontario, Canada

Objective:

Umbilical artery (UA) Doppler is a key component in the diagnosis of early-onset fetal growth restriction (FGR). However, the interpretation of UA Doppler is complicated by the considerable variability of available UA Doppler references, which can have a profound impact on the proportion of small fetuses diagnosed with FGR. Our aim was to explore the methodological factors contributing to the heterogeneity of existing references and develop a UA Doppler pulsatility index (UA-PI) reference using an approach that addresses some of the limitations of prior studies.

Study Design:

This was a retrospective longitudinal study of individuals with an uncomplicated singleton pregnancy who underwent assessment of UA Doppler at a single academic center (2012-2022) where UA Doppler is measured routinely in all ultrasound exams. We explored the effect of estimated fetal weight (EFW) percentile threshold ( >10th, >25th, or >50th centile), parity, and statistical modeling approach (LMS, quantile regression, and quantile sheets) on the reference values. Based on these findings, a final UA-PI chart was developed and compared to existing charts.

Results:

A total of 25,069 UA-PI measurements from 12,394 patients were analyzed. The study population’s EFW percentile threshold had a considerable impact on the UA-PI reference (Figure 1), whereas the effect of parity was minimal. LMS and quantile regression methods yielded similar UA-PI reference charts, unlike the quantile sheets method. Therefore, our final UA-PI reference was based on observations from fetuses with EFW >50th percentile using the LMS method. The differences between the new chart and previously published charts in the UA-PI 95th percentile are illustrated in Figure 2.

Conclusion:

To our knowledge, this study is the first to explore the impact of methodological factors on a UA-PI reference chart. The newly developed chart addresses several limitations of previous studies. As such, it may reflect more accurately the distribution of UA-PI in uncomplicated singleton pregnancies and improve the accuracy of FGR diagnosis.