Protocol - Stroke Risk in Children with Sickle Cell Disease - TCD

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Transcranial Doppler (TCD) ultrasonography is a non-imaging technique that measures the blood flow velocity in large intracranial arteries. This TCD protocol covers how to identify relevant intracranial landmarks and how to record and score TCD results.

Specific Instructions:

Results from Transcranial Doppler (TCD) ultrasound should be interpreted by a medical doctor with expertise in TCD in sickle cell disease (SCD). Additionally, the TCD results should be compared with published guidelines to determine if the subject should be receiving prophylactic red cell transfusion or require more frequent TCD or other monitoring.

The Working Group notes that blood-flow velocities indicative of stroke risk can be obtained by either TCD or Imaging Transcranial Doppler (TCDi) ultrasonography. The choice of TCD or TCDi depends on the expertise and equipment available to investigators.


Transcranial Doppler Ultrasonography

Identifying Intracranial Landmarks and Major Cerebral Arteries

Transcranial Doppler (TCD) ultrasonography provides visual landmarks to help correctly identify intracranial blood vessels. Correct identification of intracranial vessels relies on the diameter of the head, position of the transducer, angle of the transducer, depth of the Doppler sample, and direction of the blood flow. In adults, the diameter of the head is assumed to be 130-140 mm, whereas the head diameter must be measured due to variation of children’s head sizes. In children, the bitemporal diameter is measured so that the location of the midline can be calculated (half of the diameter of the head). The internal carotid artery (ICA) bifurcation is the landmark that is the reference point for all other intracranial anatomy. The depth of the ICA bifurcation is estimated to usually be 10 to12 millimeters shallower than the midline.

Recording Transcranial Doppler Ultrasonography Results

The results of the TCD are spectral waveform plots of velocity vs. time and the calculated velocity is the time averaged mean of the maximum velocity. Examiners should record the highest time-averaged mean blood-flow velocity in 2-millimeter increments in the following arteries:

  • middle cerebral artery (at three points),
  • distal internal carotid artery,
  • anterior and posterior cerebral arteries, and
  • basilar artery.


Normal: blood velocities less than 170 centimeters per second in all arteries.

Conditional: blood velocities greater than 170 centimeters per second but less than 200 centimeters per second in all arteries.

Abnormal: blood velocity of 200 centimeters per second or greater in either the internal carotid artery or the middle cerebral artery

Inadequate: if the middle cerebral artery (MCA) velocity cannot be estimated on both sides due to poor signal to noise (S/N) ratio the study is inadequate unless one side shows MCA velocity of greater than or equal to 200 centimeters per second.

Protocol Name from Source:



Personnel and Training Required
Equipment Needs

2 megahertz Doppler ultrasonogram

Requirement CategoryRequired
Major equipment Yes
Specialized training Yes
Specialized requirements for biospecimen collection No
Average time of greater than 15 minutes in an unaffected individual Yes
Mode of Administration

Clinical examination and physical measurement

Life Stage:

Toddler, Child, Adolescent


Children and adolescents aged 2 years and older with hemoglobin SS or beta-zero thalassemia disease and without a history of clinical stroke.

Selection Rationale

Transcranial Doppler (TCD) ultrasound is a non-invasive, valid and reliable method that has been used in clinical trials to select children for prophylactic blood transfusion and as a surrogate end point (stroke risk) in NIH funded clinical trials.



Common Data Elements (CDE) Stroke Transcranial Doppler Ultrasound Assessment Score 4924355 CDE Browser
Human Phenotype Ontology Sickle Cell Anemia ORPHA:232 HPO
Human Phenotype Ontology Anemia OMIM:603903 HPO
Derived Variables


Process and Review

Not applicable.


Identifying Intracranial Landmarks and Major Cerebral Arteries

Nichols, F. T., Jones, A. M., & Adams, R. J. (2001). Stoke Prevention in Sickle Cell Disease (STOP) Study Guidelines for Transcranial Doppler Testing. Journal of Neuroimaging, 11, 354-362.

Recording and Scoring Results

Adams, R.J., McKie, V.C., Hsu, L., Files, B., Vichinsky, E., Pegelow, C., Abboud, M., Gallagher, D., Kutlar, A., Nichols, F.T., Bonds, D.R., & Brambilla, D. (1998). Prevention of a first stroke by transfusions in children with sickle cell anemia and abnormal results on transcranial Doppler ultrasonography. New England Journal of Medicine, 339(1), 5-11.

General References

Adams, R. J., Brambilla, D. J., McKie, V. C., Hsu, L., Files, B., Vichinsky, E., Pegelow, C., Abboud, M., Woods, G., Olivieri, N., Driscoll, C., Miller, S., Wang, W., Hurlet, A., Scher, C., Berman, B., Carl, E. M., Nichols, F. T., Roach, S., Kutlar, A., Wright, E., Zimmerman, R. A., Gallagher, D., Waclawiw, M., & Bonds, D. (1998). Transfusion Prevents First Stroke In Children with Sickle Cell Disease: The "STOP" Study. New England Journal of Medicine July, 339(1), 5-11.

Adams, R. J. (Principal and Corresponding Author) for the: Optimizing Stoke Prevention in Sickle Cell Anemia Investigative Team (STOP 2). (2005). Discontinuing Prophylactic Transfusion to Prevent Stroke in Sickle Cell Disease. New England Journal of Medicine Dec, 353(26), 2769-2778.

Bulas, D. I., Jones, A., Siebert, J. J., Driscoll, C., O’Donnell, R., & Adams, R. J. (2000). Transcranial Doppler (TCD) screening for stroke prevention in sickle cell anemia: pitfalls in technique variation. Pediatric Radiology 30, 733-738.

Pavlakis, S. G., Rees, R. C., Huang, X., Brown, R. C., Casella, J. F., Iyer, R. V., Kalpatthi, R., Luden, J., Miller, S. T., Rogers, Z. R., Thornburg, C. D., Wang, W. C. & Adams, R. J. (2010). Transcranial doppler ultrasonography (TCD) in infants with sickle cell anemia: Baseline data from the BABY HUG trial. Pediatric Blood Cancer, 54, 256-259.

Platt, O.S. (2005). Preventing stroke in sickle cell anemia. New England Journal of Medicine, 353(26), 2743-2745.

Protocol ID:


Export Variables
Variable Name Variable IDVariable DescriptiondbGaP Mapping
PX821001090000 Highest time-averaged mean blood-flow more
velocity in the anterior cerebral artery show less
PX821001110000 Highest time-averaged mean blood-flow more
velocity in the basilar artery show less
PX821001020000 Child bitemporal diameter N/A
PX821001010000 Child head diameter N/A
PX821001080000 Highest time-averaged mean blood-flow more
velocity in the distal internal carotid artery show less
PX821001040000 Depth of the internal carotid artery (ICA) more
bifurcation show less
PX821001030000 Location of the internal carotid artery more
(ICA) bifurcation show less
PX821001050000 Highest time-averaged mean blood-flow more
velocity in the middle cerebral artery: Point 1 show less
PX821001060000 Highest time-averaged mean blood-flow more
velocity in the middle cerebral artery: Point 2 show less
PX821001070000 Highest time-averaged mean blood-flow more
velocity in the middle cerebral artery: Point 3 show less
PX821001100000 Highest time-averaged mean blood-flow more
velocity in the posterior cerebral artery show less
Blood Sciences Research
Measure Name:

Stroke Risk in Children with Sickle Cell Disease

Release Date:

July 30, 2015


A clinical test to measure the blood flow velocities in intracranial arteries. Elevated intracranial arterial blood flow rates are indicative of expanding vessel lesions and a subsequent increased risk of stroke.


This measure is used to stratify stroke risk in children to determine eligibility for prophylactic blood transfusion for stroke prevention.


Stroke, Stroke risk, Blood velocity, Transcranial Doppler ultrasonography, TCD, Imaging Transcranial Doppler ultrasonography, TCDi, Brain, Blood flow