A transcranial Doppler (TCD) scan is a specialized, painless ultrasound that measures the speed and direction of blood flow in the arteries inside your brain. Unlike regular ultrasounds that struggle to pass through bone, TCD uses low-frequency sound waves through thin areas of your skull (known as acoustic windows) to see the blood vessels.
This scan is highly important for children with sickle cell anemia, as it helps identify who has high blood flow speeds, which indicate a high risk of developing a stroke.
Common Indications for a Transcranial Doppler Scan
- Screening children (aged 2 to 16) with sickle cell disease to assess their stroke risk.
- Evaluating narrowing (vasospasm) of brain arteries after a brain bleed (subarachnoid hemorrhage).
- Checking for blockages or narrowing in the brain's main arteries.
- Monitoring blood flow in the brain during certain surgical procedures.
- Investigating symptoms of dizziness, fainting, or temporary stroke-like symptoms (TIAs).
What exactly does a transcranial Doppler scan show?
The scan measures the velocity (speed) of blood flow in the major blood vessels at the base of the brain. High blood flow speeds mean the arteries are narrowed, forcing the blood to flow faster to get through, which increases stroke risk.
How should I prepare for a transcranial Doppler scan?
No special preparation is needed. You do not need to fast. For children, it is helpful to explain that the scan is painless and uses a warm gel, so they feel relaxed and lie still.
Do I need to stop taking medication?
No. Continue taking all your medications as normal. Let the radiographer know if you are taking blood thinners or blood pressure medications.
What happens when I arrive for my scan?
You will lie down on the scan couch in a private room. The radiographer will ask you to remove any headwear, glasses, or hair accessories that block the sides of your head or the back of your neck.
How is the procedure performed?
Warm gel will be applied to specific areas of your head: the temples (in front of your ears), just above your cheekbones, and the back of your neck. The radiographer will press the hand-held probe gently against these areas. You will hear rhythmic whooshing sounds from the machine's speakers as it records your blood flow. You must lie still and remain quiet during the measurements.
How long does a transcranial Doppler scan take?
The scan takes about 30 to 45 minutes to thoroughly measure all the major arteries on both sides of the brain.
Is there any discomfort?
You will feel a firm but gentle pressure as the probe is held against your temples and the back of your neck. It is not painful, but holding still for the duration of the scan can require some patience.
Are there risks?
No. This scan uses sound waves and has no radiation, needles, or injections. It is completely safe, even for very young children.
Can children have this scan?
Yes. Children with sickle cell disease should have this scan routinely every year starting from age 2 to prevent strokes. The radiographers are specially trained to make the experience friendly and comfortable for kids.
Can I have this scan if I am pregnant?
Yes. TCD is safe to perform during pregnancy as it uses no radiation.
When will I get my results?
A radiologist will analyze the flow speeds and write a report. The results will be sent to your referring doctor within 24 hours. For sickle cell screenings, the report will clearly categorize the stroke risk as normal, conditional, or abnormal.
What if the scan finds something?
If the scan shows abnormally high flow speeds, do not panic. This finding allows your referring doctor to take immediate preventative measures, such as arranging regular blood transfusions, to significantly reduce the risk of a stroke.
Conclusion
A transcranial Doppler scan is a quick, safe, and life-saving screening tool, especially for children with sickle cell anemia. To help the session go smoothly, make sure your hair is clean and free of heavy oils or braids that cover the temples.