Approach to the Newborn Who Has Thrombocytopenia

After completing this article, readers should be able to: 1. List the platelet counts that represent mild, moderate, and severe thrombocytopenia. 2. List common causes of thrombocytopenia in sick neonates, preterm infants, and infants who have other medical conditions. 3. List the conditions characterized by physical abnormalities or dysmorphic features that commonly are associated with thrombocytopenia. 4. List potential causes of thrombocytopenia in healthy-appearing neonates. 5. Describe the clinical manifestations of and treatment for neonatal alloimmune thrombocytopenia. Platelet counts in healthy fetuses (mid-second trimester) and neonates are the same as in normal children and adults. Neonatal platelet counts of 100 to 150 × 10 3/mcL (100 to 150 × 10 9/L) represent mild thrombocytopenia, platelet counts of 50 to 100 × 10 3/mcL (50 to 100 × 10 9/L) are considered moderate thrombocytopenia, and levels less than 50 × 10 3/mcL (50 × 10 9/L) are categorized as severe thrombocytopenia. Thrombocytopenia in newborns is a result of increased platelet consumption (infections, thrombosis, immune-mediated) or decreased platelet production. In many neonates, particularly sick preterm infants, both impaired megakaryopoiesis and accelerated platelet destruction may occur simultaneously. Mild asymptomatic thrombocytopenia occurs in 1% of healthy term infants. Severe thrombocytopenia in term infants, however, is rare, and most affected infants usually are recognized because of hemorrhagic manifestations (petechiae, purpura, or frank bleeding). Any term neonate whose platelet count is less than 50 × 10 3/mcL (50 × 10 9/L) should be evaluated to establish a cause. In contrast to the rarity of thrombocytopenia in healthy term neonates, low platelet counts are noted commonly in sick infants who often are preterm. Up to 25% of infants admitted to the neonatal intensive care unit (NCIU) have thrombocytopenia. Also, in contrast to term newborns who present with hemorrhagic manifestations, most cases of thrombocytopenia in …