Sickle-cell disease not identified by newborn screening because of prior transfusion.

Erythrocyte transfusion can impair detection of sickle-cell disease, galactosemia, or biotinidase deficiency with newborn screening. We report on 4 infants with SCD in whom delayed diagnosis was associated with neonatal transfusion. In 2 cases, the initial newborn screening showed no hemoglobin S. In no case was the recommended screening >/=120 days from the last transfusion obtained. Two children had significant SCD-related morbidity before diagnosis.