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Transcranial Doppler ultrasound

Transcranial Doppler ultrasonography; TCD ultrasonography; TCD; Transcranial Doppler study

Transcranial doppler ultrasound (TCD) is a diagnostic test. It measures blood flow to and within the brain.


Cerebral aneurysm
Transient Ischemic attack (TIA)
Atherosclerosis of internal carotid artery

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:

How to Prepare for the Test

No special preparation is needed for this test. You do not need to change into a medical gown.

Remember to:

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:

Normal Results

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.

Newell DW, Monteith SJ, Alexandrov AV. Diagnostic and therapeutic neurosonology. In: Winn HR, ed. Youmans and Winn Neurological Surgery. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 410.

Sharma D, Prabhakar H. Transcranial Doppler ultrasonography. In: Prabhakar H, ed. Neuromonitoring Techniques. Cambridge, MA: Elsevier Academic Press; 2018:chap 5.


Review Date: 4/29/2023  

Reviewed By: Joseph V. Campellone, MD, Department of Neurology, Cooper Medical School of Rowan University, Camden, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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