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Transcranial Doppler (TCD) is a painless, non-invasive ultrasound test that measures blood flow inside the brain. It can detect if there is a high risk of having a stroke.
TCD uses a small device (probe) placed on the outside of the head. It records images or waveforms to show how blood is flowing through blood vessels in the brain. Like other types of ultrasound or sonography, this test uses sound waves to see inside the body or detect blood flow.
TCD can help find problems that affect blood flow to the brain such as:
Types of TCD machines include:
Both types of TCD machines measure blood flow.
All children with sickle cell anemia (HbSS) or sickle beta thalassemia (SB-0) need routine TCD tests starting at age 2. This test is an important part of your child’s care.
Regular TCD screening tests help to monitor the risk of stroke. A stroke is an injury to the brain that happens when a blood vessel is blocked.
People with sickle cell disease have red blood cells that are hard, sticky, and shaped like a banana. This can cause red blood cells to block blood vessels. This increases your child’s risk of stroke.
TCD and TCDi are safe and painless. No special preparation is needed. Your child can eat and drink normally before the test. The test usually takes up to one hour.
Your child should wear comfortable, loose-fitting clothing. Your child does not need to change into a medical gown. Remove hats, glasses, hair clips, and earrings.
Your child will lie on their back. Your child may be able to watch a show on a tablet during the exam.
A trained TCD technologist will perform the test. The technologist will put a clear gel on the side of your child’s head. This helps the ultrasound probe work better on the skin. The gel might feel cold at first. The technologist will wipe it off when the ultrasound is over.
Next, the technologist will press the ultrasound probe firmly on your child’s skin. This should not cause any pain or discomfort. Your child might feel some pressure. Your child will hear a “swooshing” sound during the test. This is the sound of blood flowing through the arteries.
The technologist might move the probe back and forth in a certain place or press more firmly in some places. This helps get the best measurement of blood flow.
Your child will be awake during the exam. It is important for your child to:
Your child cannot eat, drink, suck on a pacifier, or talk during the exam. If your child has trouble lying still or being quiet, let the care team know.
A doctor called a radiologist will review the scans. They will look carefully at how fast blood is moving through your child’s brain. Results will be shared with other members of your child’s care team.
Below is a list of the possible test results and what each generally means. Your care team will explain your child’s results and let you know what follow up care is needed. Always follow the specific recommendations given by your care team.
Reviewed: February 2024