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Aaskullxr

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

This test measures the thickness of soft tissue at the A-point (nasion) on a skull X-ray, often used to help identify certain genetic conditions.

Quick summary

{"Measures soft tissue thickness at the A-point of the skull via X-ray","Helps doctors assess for genetic syndromes like Down syndrome","Non-invasive imaging test using low radiation","Part of cardiac evaluation in congenital conditions","Results are compared with normal reference values by age"}

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

Key facts at a glance

LOINC
60673-1
Short code
STTA-point
Synonyms
A-A' Skull XR
Category
cardiac
Sample
serum
Container
Not applicable (radiographic imaging study)
Units
N/A
Ref low
19
Ref high
23
Fasting
false
Population
adult
Sex
all
Age range
0–100 years
Method
xr-measured
CPT
70350
SNOMED
363517005
Specimen volume
Not applicable (imaging study)
Stability
Not applicable (imaging study)
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
24–72 hours
Order
routine

What is this test?

The A-point soft tissue thickness test is a diagnostic measurement performed on skull X-ray images. The A-point, also known as the nasion, is the junction where the frontal bone meets the nasal bones. This test measures the thickness of the soft tissue at this specific location on the skull.

How is the test performed?

During the test, you will have a standard skull X-ray taken. The technician will position your head properly to capture a clear side view (lateral view) of the skull. The measurement is then taken by a radiologist or trained clinician using the X-ray image to determine the soft tissue thickness at the A-point.

Why is it ordered?

This test is often ordered as part of a broader cardiac evaluation, especially in children with suspected congenital heart disease or genetic syndromes. Abnormal soft tissue thickness at the A-point can be associated with certain genetic conditions that also affect the heart.

Reference range

19-23 mm in adults; varies by age, sex, and ethnicityN/A

Specimen: serum

Remove all metallic objects, hair accessories, and orthodontic appliances before imaging. Patient should position head in standardized Frankfort horizontal plane.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

Does the test hurt?
No, the test is painless. It is a simple X-ray examination that takes only a few minutes. The radiation exposure is very low and considered safe for diagnostic purposes.
How long does it take to get results?
Results are usually available within 1-2 days. Your doctor will discuss the findings with you during a follow-up appointment.
Do I need to prepare for the test?
No special preparation is needed. You may be asked to remove jewelry or metal objects that might interfere with the X-ray image.
What do abnormal results mean?
Abnormal measurements may suggest the need for further genetic evaluation. However, this test alone cannot diagnose a condition—it is used alongside other clinical findings and tests.
  1. 1
    Radiopaedia - Skull X-raySource
  2. 2
    LOINC Code ReferenceSource

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