Result of TCD | Cerebral Blood Flow Velocity (cm/s) | Frequency of exam |
Absence of window | - | Use other imaging resource to analyze cerebrovascular events. |
Technical difficulty due to lack of cooperation | - | Repeat every three months; evaluation by another examiner. |
Low cerebral blood flow velocity | 70 | Repeat after 1 month. |
Normal cerebral blood flow velocity | <170 | Repeat annually. |
Low conditional | Between 170 and 184 | Repeat at three-month intervals. If the subsequent results are normal, adopt the normal conduct. |
High conditional | Between 185 and 199 | Repeat after 1 month. In case of unchanged examinations, it is recommended to repeat every three months. In case of two consecutive abnormal results, it is recommended to discuss the risk of strokes and consider a chronic transfusion regimen. |
Abnormal | Between 200 and 219 | Repeat after 1 month. If the velocity remains higher or equal to 200, it is recommended to discuss the risk of strokes and consider chronic transfusion regimen. If the result decreases to 170-199, it is recommended to repeat it after one month (if high conditional—between 185 and 199); or repeat it after 6 months (if conditional low—between 170 and 184). If the result is normalized (<170), it is recommended to repeat in 1 year. |
| More than 220 | Discuss imminent risk of strokes and consider chronic transfusion regimen. |