Angiographic measurement of blood flow velocity in the skull (e.g., transcranial Doppler ultrasound)
This test measures how fast blood flows through arteries in your skull using ultrasound. It helps assess blood circulation in the brain and may be used to check for conditions like blockages or abnormal blood flow patterns.
["This test helps evaluate brain circulation and identify potential issues with blood flow."]
Key facts at a glance
- LOINC
- 32937-5
- Short code
- FH-NPg Angle Skull XR
- Synonyms
- FH-NPg Angle Skull XR
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- xr-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 investigate symptoms such as headaches, dizziness, or neurological concerns, or to monitor conditions like migraines, stroke risk, or vascular abnormalities in the brain. It can also be part of a broader evaluation for conditions like transient ischemic attacks (TIAs) or carotid artery disease.
What to Expect During the Test
The test involves placing gel on your head and using a small handheld device (probe) to send sound waves through your blood vessels. You may hear a steady beeping or buzzing noise as the probe moves. It usually takes about 15–30 minutes and is generally painless.
Common Conditions Monitored
This test is often used to monitor blood flow in conditions such as migraines, carotid artery stenosis, or suspected vascular issues in the brain. It can also help assess blood flow before or after certain surgeries or treatments.
Preparation for the Test
No special preparation is needed. You may eat and drink normally before the test, but let your provider know if you’re taking blood thinners or have any concerns about head movement.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Abnormal blood flow velocities may indicate narrowed arteries, blockages, or other vascular problems. Low flow could suggest poor circulation, while high or turbulent flow might signal stenosis or other vascular abnormalities. Results help guide treatment decisions, such as medication adjustments or interventions like angioplasty.
Short name
Skull Blood Flow Velocity (TCD)
Frequently asked questions
What does a normal result mean?
How often will I need this test?
Can I drive or operate machinery after the test?
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