The Seasoned Sonographer

Umbilical Artery Doppler & FGR: Understanding Placental Physiology

Episode Summary

Lynn Flamm, RDMS, is joined by OB/Gyn physician Dr. Danielle Tomevi to discuss Umbilical Artery Doppler in the evaluation and management of fetal growth restriction (FGR). This episode connects fetal circulation, placental insufficiency physiology, proper Doppler technique, interpretation of PI and RI, abnormal findings, and ACOG-aligned monitoring principles. Sonographers will learn when Dopplers are indicated — and why understanding physiology elevates clinical care.

Episode Notes

In this episode we discuss:

• Definition of FGR (EFW <10% or AC <10%)
• Early asymmetric FGR and the significance of abdominal circumference
• Causes of FGR
• Fetal circulation and placental resistance
• Proper umbilical artery Doppler technique
• S/D ratio, PI, RI
• Absent and reversed end-diastolic flow
• ACOG-aligned monitoring and delivery principles
• When sonographers should add UA Dopplers
• Why UA Dopplers are clinically valid after 24 weeks gestation

Referenced guidance:
American College of Obstetricians and Gynecologists Practice Bulletin on Fetal Growth Restriction

© 2026 Lynn Flamm, RDMS
Founder & CEO, Sono Techniques Academy, LLC
Host, The Seasoned Sonographer Podcast

For educational purposes only. Clinical management should follow current ACOG guidance and physician direction.