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Maximum Fetal Mandible Length Measurement

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

This test measures the longest distance across the fetal mandible (jawbone) using ultrasound imaging during pregnancy. It helps assess fetal growth and development.

Quick summary

["This test supports prenatal monitoring of fetal jaw development."]

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

Key facts at a glance

LOINC
53670-6
Short code
Fet Mandible Length.max US.meas
Synonyms
Fet Mandible Length.max 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 Is This Test Done?

Your healthcare provider may order this test to evaluate fetal growth patterns, especially if there are concerns about potential developmental issues or to monitor progress in cases of suspected intrauterine growth restriction.

How Is the Test Performed?

The test involves an ultrasound scan during pregnancy. A trained technician uses high-frequency sound waves to create images of the fetal mandible. The measurement is taken from the widest point of the fetal jaw.

What Does the Result Mean?

Results are compared to standard fetal growth charts to determine if the fetal mandible appears within expected ranges for gestational age. Deviations may prompt further evaluation.

When Might You Need Follow-Up?

If the measurement falls outside typical ranges, additional ultrasounds or consultations with a specialist (e.g., pediatrician or genetic counselor) may be recommended to investigate underlying causes.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Fetal Mandible Length (Max)

Frequently asked questions

What does a measurement outside normal ranges indicate?
A measurement outside normal ranges may signal concerns about fetal growth or development, prompting further prenatal assessments to identify any underlying issues.
Is this test painful or uncomfortable?
No, this test is completely painless. You may feel a slight pressure or warmth during the ultrasound, but it is a routine part of prenatal care.
How often is this test performed during pregnancy?
The frequency depends on your pregnancy status and healthcare provider’s recommendations. It may be done once or multiple times during pregnancy, especially if monitoring fetal development closely.
  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