Skip to content

Fetal Radius Length Measurement

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

This test measures the length of the radius bone in a fetus, typically performed during prenatal ultrasound imaging to assess growth and development.

Quick summary

["A fetal radius length check helps monitor fetal development during pregnancy."]

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

Key facts at a glance

LOINC
53699-5
Short code
Fet Radius-R Length US.meas
Synonyms
Fet Radius-R Length US.meas
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-measured
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 are pregnant and there are concerns about your baby’s growth, such as suspected intrauterine growth restriction (IUGR) or other developmental issues. It can also be part of routine prenatal care to track fetal progress.

How the Test Works

This is not a blood or lab test in the traditional sense. Instead, it involves an ultrasound scan where a specialized imaging device measures the length of the radius bone in your fetus. The technician will use real-time imaging to take precise measurements.

What to Expect

You will likely lie on your back on an exam table with a pillow under your hips. A gel is applied to your abdomen to allow the ultrasound probe to glide smoothly over your skin. The procedure is quick, painless, and does not involve radiation beyond standard ultrasound safety limits.

Preparation

No special preparation is needed for this test. You can eat, drink, and move around as usual. However, you may want to wear comfortable clothing and avoid applying lotions or creams on your abdomen the day of the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Fetal Bone Length

Frequently asked questions

What does a fetal radius length test measure?
This test measures the length of the radius bone in your fetus using ultrasound imaging. It helps healthcare providers assess fetal growth and development during pregnancy.
Is this test painful?
No, this test is not painful. It involves a brief ultrasound scan that feels like a gentle pressure on your abdomen. The procedure is safe and does not involve needles or blood draws.
When might I need this test?
You may need this test if you have concerns about your baby’s growth, such as suspected intrauterine growth restriction (IUGR), or if your healthcare provider is monitoring fetal development during pregnancy.
  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