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PubMed This is a summary of 21 peer-reviewed journal articles Updated
Obstetrics

Understanding Your Ultrasound & Doppler Reports

At a Glance

Ultrasound and Doppler reports for placental insufficiency measure your baby's size and blood flow to check their well-being. Key markers include the umbilical artery Doppler for placental blood flow, and the cerebroplacental ratio to see if the baby is prioritizing oxygen to their brain.

Reading an ultrasound report for a baby with growth concerns can feel like trying to decipher a secret code. These reports use specific measurements and ratios to “check in” on how well the placenta is supporting your baby [1][2]. Understanding these terms can help you have more productive conversations with your medical team.

The Size Measurements: EFW and AC

When a doctor says your baby is in a certain “percentile,” they are comparing your baby’s size to 100 other babies at the exact same stage of pregnancy [3][4]. If your baby is in the 10th percentile, it means 90 babies are larger and 10 are smaller [3].

On your report, you will see two main size markers:

  • Estimated Fetal Weight (EFW): A calculation based on the baby’s head, belly, and thigh bone [1].
  • Abdominal Circumference (AC): The measurement around the baby’s belly [2]. This is often the most sensitive marker for placental issues because when a baby isn’t getting enough nutrients, they tend to use their energy for vital organs first, making the belly measurement smaller [2][5].

The “Plumbing” Check: Umbilical Artery (UA) Doppler

The Umbilical Artery (UA) Doppler is an ultrasound that measures the resistance of blood flow from the baby back to the placenta [6][7].

  • Elevated Resistance (High Pulsatility Index): The blood is having a hard time flowing into the placenta, suggesting the “supply line” is narrowed [6]. You might see this written as an elevated “Pulsatility Index” (PI).
  • Absent End-Diastolic Flow (AEDF): Between heartbeats, the blood flow in the umbilical cord completely stops instead of continuing to move forward [8][9].
  • Reversed End-Diastolic Flow (REDF): Between heartbeats, the blood actually starts to flow backward toward the baby. This is a sign of severe placental resistance and requires immediate medical attention [8][9].

The “Survival” Check: Brain-Sparing and CPR

When a placenta isn’t working perfectly, the baby is smart—they prioritize sending oxygen-rich blood to their brain at the expense of other organs [10][11]. This is called brain-sparing [12].

Doctors measure this using two specific markers:

  1. Middle Cerebral Artery (MCA): This measures blood flow within the baby’s brain. If the vessels here are very open (low resistance), it shows the baby is trying to pull in as much oxygen as possible [13][14].
  2. Cerebroplacental Ratio (CPR): This compares the blood flow in the brain (MCA) to the blood flow in the umbilical cord (UA) [13][15]. A low CPR tells doctors the baby is in “protection mode” and helps them decide if it is time for the baby to be born [16][17].

Growth Scan Checklist

When you receive a growth ultrasound report, ensure the following items are included and discussed:

  • [ ] Estimated Fetal Weight (EFW) percentile [18]
  • [ ] Abdominal Circumference (AC) percentile [19]
  • [ ] Amniotic Fluid Index (AFI) (Because babies who aren’t getting enough nutrients often pee less, leading to lower fluid levels around the baby) [20]
  • [ ] Umbilical Artery (UA) Doppler results [18]
  • [ ] Middle Cerebral Artery (MCA) Doppler results [21]
  • [ ] Comparison to the previous scan to see the growth “velocity” or trend [19]

Common questions in this guide

What does an elevated resistance or high pulsatility index mean on an umbilical artery Doppler?
Elevated resistance means blood is having a hard time flowing from the baby into the placenta. This suggests the blood vessels in the placenta are narrowed, reducing the supply of vital nutrients and oxygen to your baby.
What is "brain-sparing" in a baby?
Brain-sparing happens when a baby prioritizes sending oxygen-rich blood to their brain instead of other organs due to poor placental function. Doctors measure this by checking blood flow in the baby's brain and comparing it to the umbilical cord blood flow.
Why is abdominal circumference (AC) an important ultrasound measurement?
Abdominal circumference is often the most sensitive marker for placental issues. When a baby isn't getting enough nutrients from the placenta, they use their energy to protect vital organs first, which causes their belly measurement to be smaller.
What does a low cerebroplacental ratio (CPR) mean on my ultrasound report?
The cerebroplacental ratio compares blood flow in the baby's brain to the blood flow in the umbilical cord. A low CPR indicates the baby is in a protective, brain-sparing mode, which helps doctors decide if it is time to deliver.
What does absent end-diastolic flow (AEDF) mean?
Absent end-diastolic flow means that between heartbeats, blood flow in the umbilical cord completely stops instead of moving forward. This is a sign of significant placental resistance that requires close medical monitoring.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.What were the exact percentiles for the Abdominal Circumference (AC) and the Estimated Fetal Weight (EFW)? Is one significantly lower than the other?
  2. 2.If the Umbilical Artery Doppler was abnormal, was it intermittent or persistent?
  3. 3.Is the Cerebroplacental Ratio (CPR) showing that my baby is in a "brain-sparing" mode?
  4. 4.Are the Doppler measurements stable, or have they changed since our last scan?
  5. 5.Based on these specific Doppler findings, how many times per week should we be monitoring the baby's heart rate and blood flow?

Questions For You

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References

References (21)
  1. 1

    Artificial intelligence assistance for fetal development: evaluation of an automated software for biometry measurements in the mid-trimester.

    Han X, Yu J, Yang X, et al.

    BMC pregnancy and childbirth 2024; (24(1)):158 doi:10.1186/s12884-024-06336-y.

    PMID: 38395822
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    Diagnostic performance of third-trimester ultrasound for the prediction of late-onset fetal growth restriction: a systematic review and meta-analysis.

    Caradeux J, Martinez-Portilla RJ, Peguero A, et al.

    American journal of obstetrics and gynecology 2019; (220(5)):449-459.e19 doi:10.1016/j.ajog.2018.09.043.

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    Fetal growth restriction and intra-uterine growth restriction: guidelines for clinical practice from the French College of Gynaecologists and Obstetricians.

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    Best practice & research. Clinical obstetrics & gynaecology 2018; (49()):3-15 doi:10.1016/j.bpobgyn.2018.02.005.

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    Using fetal abdominal circumference growth velocity in the prediction of adverse outcome in near-term small-for-gestational-age fetuses.

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    Doppler Ultrasound of the Umbilical Artery: Clinical Application.

    Rocha AS, Andrade ARA, Moleiro ML, Guedes-Martins L

    Revista brasileira de ginecologia e obstetricia : revista da Federacao Brasileira das Sociedades de Ginecologia e Obstetricia 2022; (44(5)):519-531 doi:10.1055/s-0042-1743097.

    PMID: 35405757
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    Achieving orphan designation for placental insufficiency: annual incidence estimations in Europe.

    Spencer R, Rossi C, Lees M, et al.

    BJOG : an international journal of obstetrics and gynaecology 2019; (126(9)):1157-1167 doi:10.1111/1471-0528.15590.

    PMID: 30576053
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    Risk of fetal death in growth-restricted fetuses with umbilical and/or ductus venosus absent or reversed end-diastolic velocities before 34 weeks of gestation: a systematic review and meta-analysis.

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    Perinatal outcome of growth restricted fetuses with abnormal umbilical artery Doppler waveforms compared to growth restricted fetuses with normal umbilical artery Doppler waveforms at a tertiary referral hospital in urban Ethiopia.

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    Effects of Plasmodium falciparum infection on umbilical artery resistance and intrafetal blood flow distribution: a Doppler ultrasound study from Papua New Guinea.

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    Does Hypoxia Prompt Fetal Brain-Sparing in the Absence of Fetal Growth Restriction?

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    The effect of loading dose of magnesium sulfate on uterine, umbilical, and fetal middle cerebral arteries Doppler in women with severe preeclampsia: A case control study.

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This guide to interpreting ultrasound and Doppler reports is for informational purposes only. Always consult your obstetrician or maternal-fetal medicine specialist to understand your specific scan results and care plan.

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