Transcranial Doppler Tests



A transcranial Doppler (TCD) test is an ultrasound-based medical test. You may already be familiar with ultrasound technology because of its wide range of uses in diagnosing medical conditions and monitoring during pregnancy. A TCD is an ultrasound performed at the base of the brain to provide information about the speed of blood flow in the brain and assess the risk of a stroke.

What you can expect

A TCD test doesn’t require any preparation on your part. The process of a TCD test involves the following:

  1. You’ll be asked to lie on an examining table or sit upright.
  2. At the beginning of the test, the TCD technician will apply a harmless gel to the skin over your temple to help the sound waves transmit into your body.
  3. The TCD technician will then pass a handheld wand called a transducer over your temple. The transducer emits sound waves that bounce off blood cells and are picked up again by the transducer while a computer interprets these sound-wave signals.
  4. To assess your stroke risk, the TCD technician may pass the wand over your carotid arteries (arteries in your neck) and arteries at the base of your brain.
  5. After the test, you’ll be able to get back to your day and resume your regular activities.


There are no known harmful effects of ultrasound or repeated ultrasounds.