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Fetal Brain Perfusion-Derived Mean Estimated Gestational Age (GA) from Doppler Ultrasound

Published: August 9, 2026Updated: August 16, 2026

This test uses fetal brain blood flow measurements from ultrasound to estimate how far along your pregnancy you may be.

Quick summary

["Ultrasound-based gestational age estimation using fetal brain perfusion patterns."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
11821-6
Short code
Fet BPD.mean Est from GA
Synonyms
Fet BPD.mean Est from GA
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
estimated-from-gestational-age
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What This Test Measures

The test evaluates blood flow dynamics in specific fetal brain regions (cerebral arteries) using Doppler ultrasound technology. It calculates a mean value representing how these patterns compare to typical gestational age-related patterns observed in healthy pregnancies.

Why It’s Done

Your healthcare provider may order this test if you have concerns about pregnancy timing (e.g., suspected early or late gestation), or if standard ultrasound measurements are unclear. It helps confirm gestational age when other methods are inconclusive.

How It Works

During the ultrasound, a transducer detects blood flow velocities in fetal cerebral arteries. Specialized software analyzes these waveforms to generate a perfusion-derived estimate of gestational age, often compared to your last menstrual period or other markers.

What to Expect

You’ll lie on your back or side as the technician applies gel to your abdomen. The ultrasound probe moves gently over your belly while measuring fetal brain blood flow. The process takes about 15–30 minutes and is painless.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

Is this test the same as a standard ultrasound?
No. While both use ultrasound, this test specifically focuses on fetal brain perfusion patterns rather than measuring fetal size or organ development.
How accurate is this test?
Accuracy varies by provider and equipment, typically within ±3–5 days of actual gestational age. It’s most reliable when used alongside other prenatal markers.
Can I eat or drink before this test?
No special preparation is needed. You may eat/drink as usual, but avoid caffeine if sensitive to it, as it may affect blood flow measurements.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy