Fetal Radius Length from Gestational Age (GA) Estimate
This test measures the length of the fetal radius bone to help estimate how far along in pregnancy you are.
["Assessing fetal development timing with bone measurements during pregnancy."]
Key facts at a glance
- LOINC
- 33180-1
- Short code
- Fet Radius Length from GA.Jeanty83
- Synonyms
- Fet Radius Length from GA.Jeanty83
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- us-estimated-from-jeanty
- 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
Why This Test Is Done
Your healthcare provider may order this test if you’re at higher risk for pregnancy complications, such as gestational diabetes, preeclampsia, or other conditions that could affect fetal growth. It can also be used to monitor fetal development in cases where other prenatal tests suggest potential concerns.
How the Test Works
The test involves ultrasound imaging, where a transducer sends sound waves through your abdomen to capture images of your baby’s bones. The length of the fetal radius (one of the forearm bones) is measured and compared to standard growth charts based on gestational age to estimate how far along you are.
Sample Collection
No special preparation is needed. You’ll lie on your back on an exam table, and a gel is applied to your abdomen. The ultrasound probe is gently placed on your skin to capture images of your baby’s bones.
What to Expect After the Test
After the ultrasound, you can usually return to your normal activities immediately. Your provider will discuss the results with you, which may include confirmation of your due date or additional monitoring if needed.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This measurement is primarily used to confirm or refine your estimated due date, especially in cases where other prenatal tests (like dating ultrasound) may have provided less precise results. It can also help identify potential fetal growth concerns early, allowing for timely interventions if necessary.
Short name
Fetal Bone Measurement
Frequently asked questions
What does a fetal radius length measurement tell me about my pregnancy?
Is this test painful or uncomfortable?
How often is this test done during pregnancy?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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