Transcranial Doppler Ultrasound Velocity Measurements in Children With Sickle Cell Disease in Kenya.

Background: Sickle cell disease (SCD) is the most common inherited haemoglobinopathy and poses a high public health burden in Sub-Saharan Africa. Children with sickle cell anaemia are at a highrisk of ischemic stroke, and transcranial Doppler (TCD) ultrasonography helps identify those at highest risk for primary stroke prevention. Objective: To determine the prevalence of abnormal cerebral blood flow velocity (CBFV) in children with SCD and describe CBFV in children without SCD. Methods: We conducted a two-component study comprising a retrospective review and a cross-sectional assessment. TCD measurements from 143 children with confirmed SCD aged 2-16 years were reviewed. In a cross-sectional arm, children without SCD aged 3-11 years ( Results: Among 143 children screened, all of whom were receiving hydroxyurea, 1.4% had high TCD velocities (≥ 200 cm/s), while 4.9% had low velocities (< 50 cm/s). TCD velocities were not associated with demographic/clinical characteristics or haemoglobin levels. Symmetric MCA flows with wide depth and velocity range variability were observed. In children without SCD, all MCA velocities were within the normal range (50-149 cm/s), showed right-left symmetry, declined with age, and were broadly similar by gender. Conclusion: The prevalence of abnormal TCD velocities was low in children with SCD receiving universal hydroxyurea. In children without SCD, MCA velocities were normal and declined with age, providing local reference values. The observed variability in CBFV supports continued annual TCD screening and repeat scans to confirm stroke-risk classification. Trial Registration: The authors have confirmed clinical trial registration is not needed for this submission.