Transcranial Doppler (TCD) Screening
Children with sickle cell disease (SCD) have a higher risk of stroke because sickle-shaped red blood cells can damage and narrow blood vessels in the brain.
A screening test called Transcranial Doppler (TCD) helps doctors detect stroke risk early — before symptoms appear. When risk is identified early, treatment can prevent many strokes.
What Is a Transcranial Doppler?
Transcranial Doppler (TCD) is a non-invasive ultrasound test that measures how fast blood flows through major brain arteries.
Faster blood flow may mean the artery is narrowing.
For example, a velocity of 200 cm/s or higher in the MCA or ICA indicates increased stroke risk.
TCD screening uses sound waves, not radiation, and does not require needles or sedation.
Why Children With SCD Need TCD Screening
Children with certain types of sickle cell disease — especially HbSS and HbSβ⁰-thalassemia — have the highest stroke risk.
TCD screening allows doctors to identify narrowing blood vessels before symptoms occur and begin preventive treatment.
When and How Often Is TCD Done?
Guidelines recommend:
- Begin screening at age 2
- Continue yearly through age 16 (if no prior stroke)
Children with concerning results may need testing more often. Screening may stop in late adolescence if results remain normal.
What Happens During the Test?
The exam takes about 30–45 minutes.
During the procedure:
- The child lies comfortably on a bed
- The technologist measures head width (bitemporal diameter) to locate the brain’s midline
- A small probe is placed gently against the head
- Blood flow is measured in multiple arteries on both sides
The test is painless, and normal activities can resume immediately afterward.
How TCD Prevents Stroke
If results are abnormal, doctors usually begin regular red blood cell transfusion therapy.
Transfusions lower the number of sickle cells circulating in the bloodstream and protect the brain’s blood vessels. Clinical studies show this treatment greatly reduces the risk of first stroke.
If iron builds up from transfusions, medications called iron chelation therapy may also be used.
Why This Screening Matters
TCD screening is one of the most effective preventive tools in sickle cell care.
Early detection and early treatment protect brain development, learning ability, and long-term health.
Key Takeaways
- TCD is safe, painless, and quick
- It identifies stroke risk before symptoms appear
- Children with HbSS or HbSβ⁰ should be screened yearly from ages 2–16
- Abnormal results allow treatment that prevents stroke
If your child has sickle cell disease and has not had a TCD screening, speak with your sickle cell care team about scheduling this important test.