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Transcranial Doppler Ultrasound (TCD) and Sickle Cell Disease

What is a transcranial doppler ultrasound?

Transcranial doppler ultrasound is a test that uses sound waves to see the inside of the body. You might here it called “TCD” by your child’s care team. This test shows how fast blood moves through the blood vessels in your child’s brain.

When your child has sickle cell disease, they have a higher risk of having a stroke than other children. A TCD checks your child’s risk of a stroke. 

All children with sickle cell anemia (HbSS) or sickle beta thalassemia (SB-0) need this test starting at age 2. Transcranial doppler ultrasounds can help the care team find:

  • Objects blocking normal blood flow, such as clots
  • Blood vessels that are getting narrow

Both these things raise your child’s risk of a stroke. That means this test is an important part of your child’s care. 

What to expect

A nurse who is trained to do TCD does this test. 

If you or your child had regular ultrasound before, TCD works the same way. The test uses a small probe that records images of the blood flow inside your child’s head. The images show how well blood is flowing through the blood vessels.

Your child should wear comfortable, loose-fitting clothing and take off:

  • Hats
  • Glasses
  • Hair clips 
  • Earrings 

Your child can eat and drink normally before the test.

Your child will lie on their back. The nurse will put a clear gel on your child’s head. This helps the ultrasound probe work better on the skin. The gel might feel cold at first. The nurse will wipe it off when the ultrasound is over. 

Next, the nurse will press the ultrasound probe firmly on your child’s skin. The nurse 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 how blood is moving. 

During the exam, your child needs to:

  • Be awake
  • Lie still
  • Be as quiet as possible

Your child cannot eat, drink, or suck on a pacifier during the exam. 

If your child has trouble lying still or being quiet, let the care team know.  

Transcranial doppler ultrasound results

A doctor trained to understand TCD and other imaging tests will see the results first. This doctor is called a radiologist. The radiologist will look carefully at how fast blood is moving through your child’s brain. Then the radiologist sends a report to other members of your child’s care team.

Below is a list of the possible results and what each one means.

  • Normal—Your child has a low chance of having a stroke. They will have another TCD in 1 year. It might be sooner if the care team recommends it, though. 
  • Conditional—Your child has a medium chance of having a stroke. They need another TCD in 3 to 6 months. It might be sooner if the care team recommends it. A care team member may also call to talk with you about your child’s stroke risk.
  • Abnormal—Your child has a high chance of having a stroke. They will need another TCD in 2 to 4 weeks, depending on what the care team decides. A care team member may call to talk about your child’s stroke risk.
  • Limited—The nurse could not take all the pictures needed to learn your child’s stroke risk. So your child’s stroke risk is not known. If this happens, the nurse will tell you at the exam. Your care team will tell you when your child can have another TCD.

Transcranial doppler ultrasound benefits and risks


  • Ultrasound gives a clear picture of your child’s blood vessels.
  • Ultrasound is extremely safe. It does not use radiation.
  • A TCD does not go inside the body. It does not use needles.
  • An ultrasound might be uncomfortable for a short time, but it almost never hurts.


Transcranial doppler ultrasound does not have any harmful effects.

Key Points

  • Transcranial doppler ultrasound is a test that uses sound waves to see the inside of the body.
  • Transcranial doppler ultrasound, or TCD, is an important test for children with certain types of sickle cell disease.
  • This test can help determine your child’s risk for stroke.
  • Your child should wear comfortable clothes to the test. They can eat normally before the test.
  • Your child’s care team will talk about the results with you.

Reviewed: September 2022