Transient pseudothrombocytopenia (PTCP) in the neonate due to the mother

Thrombocytopenia with platelet count <50×10⁹/L is common laboratory finding in a severely ill newborn in neonatal intensive care units (ICU). Neonates with severe thrombocytopenia are at risk of bleeding. Most dangerous is intracerebral hemorrhage (ICH) frequently leading to death or lifelong neurological sequels. Pseudothrombocytopenia (PTCP) is a rare in vitro phenomenon of falsely low platelet count determined on hematology analyzers due to platelet clumping in ethylenediaminetetraacetic acid (EDTA) anticoagulated blood. PTCP was also reported in pregnant women with isolated thrombocytopenia. EDTA-PTCP in the neonate due to the transplacental transmission of maternal antibodies has been reported only in a few cases. Although PTCP is rare phenomenon, it should always be excluded in newborns with isolated thrombocytopenia to avoid erroneous interpretation of platelet and leukocyte count, unnecessary laboratory investigation of false positive antiplatelet antibodies and needless platelet transfusions. We report on two cases of transient PTCP in a neonate due to transplacental transfer of maternal EDTA-dependent autoantibodies of IgG class from the same mother.