Transcranial doppler ultrasound (TCD) is a diagnostic test. It measures blood flow to and within the brain.
Transcranial Doppler ultrasonography; TCD ultrasonography; TCD; Transcranial Doppler study
How the Test is Performed
TCD uses sound waves to create images of the blood flow inside the brain.
This is how the test is performed:
- You lie on your back on a padded table with your head and neck on a pillow. Your neck is stretched slightly. Or you may sit on a chair.
- The technician applies a water-based gel on your temples and eyelids, under your jaw, and at the base of your neck. The gel helps the sound waves get into your tissues.
- A wand, called a transducer, is moved over the area being tested. The wand sends out sound waves. The sound waves go through your body and bounce off the area being studied (in this case, your brain and blood vessels).
- A computer looks at the pattern that the sound waves create when they bounce back. It creates a picture from the sound waves. The Doppler creates a "whooshing" sound, which is the sound of your blood moving through the arteries and veins.
- The test can take 30 minutes to 1 hour to complete.
How to Prepare for the Test
No special preparation is needed for this test. You do not need to change into a medical gown.
- Remove contact lenses before the test if you wear them.
- Keep your eyes closed when gel is applied to your eyelids so you don't get it in your eyes.
How the Test will Feel
The gel may feel cold on your skin. You may feel some pressure as the transducer is moved around your head and neck. The pressure should not cause any pain. You may also hear a "whooshing" sound. This is normal.
Why the Test is Performed
The test is done to detect conditions that affect blood flow to the brain:
- Narrowing or blockage of the arteries in the brain
Strokeor transient ischemic attack(TIA)
- Bleeding in the space between the brain and the tissues that cover the brain (
- Ballooning of a blood vessel in the brain (
- Change in pressure inside the skull (intracranial pressure)
Sickle cell anemia, to assess stroke risk
A normal report shows normal blood flow to the brain. There is no narrowing or blockage in the blood vessels leading to and within the brain.
What Abnormal Results Mean
An abnormal result means an artery may be narrowed or something is changing the blood flow in the arteries of the brain.
There are no risks with having this procedure.
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Ellis JA, Yocum GT, Ornstein E, Joshi S. Cerebral and spinal cord blood flow. In: Cottrell JE, Patel P, eds. Cottrell and Patel's Neuroanesthesia. 6th ed. Philadelphia, PA: Elsevier; 2017:chap 2.
Matta B, Czosnyka M. Transcranial doppler ultrasonography in anesthesia and neurosurgery. In: Cotrell JE, Patel P, eds. Cottrell and Patel's Neuroanesthesia. 6th ed. Philadelphia, PA: Elsevier; 2017:chap 7.
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Review Date: 29/04/2023
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