Understanding Your Diagnostic Test: What You Need to Know
A radiological measurement that evaluates the relationship between facial bones using CT scan imaging.
{"Measures the angle between facial bone structures on CT scan","Helps diagnose facial skeletal abnormalities","Used for surgical planning and orthodontic treatment"}
Key facts at a glance
- LOINC
- 32929-2
- Short code
- ANB Angle Skull CT
- Synonyms
- ANB Angle Skull CT
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ct-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
This test is a diagnostic evaluation that helps your healthcare provider assess your overall health, detect possible medical conditions early, and guide decisions about your ongoing care based on accurate results.
This test measures a specific angle on a skull CT scan. It calculates the angle between two lines: one drawn from point A (a point on the upper jaw) to the nasion (the bridge of the nose), and another from the nasion to point B (a point on the lower jaw). This measurement helps doctors evaluate the spatial relationship between the upper and lower jaws.
How the test is performed depends on the type your doctor has ordered. In many cases, a trained healthcare professional collects a small sample of blood, urine, or other tissue, which is then sent to a laboratory for analysis. The procedure is usually quick, and most people can return to their normal activities right afterward.
A CT scan of the skull is performed first. Then, using specialized imaging software, the technician or doctor identifies specific anatomical landmarks (point A, nasion, and point B) on the CT images and calculates the angle between the lines connecting these points. This is a non-invasive procedure that uses X-ray technology to create detailed cross-sectional images of the skull and facial bones.
Your doctor may recommend this test to help find the cause of symptoms you are experiencing, screen for conditions before they cause problems, monitor an ongoing illness, or check how well a current treatment is working. Timely results can help your care team make informed decisions and start the right treatment sooner.
Your doctor may order this test if you have: facial asymmetry, jaw misalignment, sleep apnea symptoms, planning for orthognathic (jaw) surgery, cleft lip or palate, facial trauma, or dental/orthodontic concerns. The measurement helps healthcare providers assess the severity of jaw positioning issues and plan appropriate treatment.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This angle measurement is important for diagnosing skeletal malocclusion (improper bite), planning corrective jaw surgery, evaluating facial asymmetry, and assessing treatment outcomes. Normal values vary, but significant deviations may indicate the need for orthodontic or surgical intervention. This test provides objective data that helps surgeons plan procedures like jaw advancement or reduction.
Frequently asked questions
Does the CT scan involve radiation?
How long does the test take?
Do I need to prepare for the test?
When will I get the results?
Sources
- 1
- 2
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