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EDTA-dependent pseudothrombocytopenia (PTCP) in the neonate due to the mother: case report

Pseudothrombocytopenia (PTCP) is a phenomenon of falsely low pla- telet count determined on hematology analyzers due to platelet clumping in ethylenediaminetetraacetic acid (EDTA) anticoagulated blood. In EDTA-PCTP platelet autoantibodies directed to the platelet membrane GP IIb-IIIa complex modified by EDTA induce in vitro platelet aggregate or agglutinate formation, which finally leads to a falsely decreased platelet count. Blood smear done from EDTA anticoagulated blood searching for platelet aggregates, along with determination of complete blood count (CBC) in EDTA and sodium citrate anticoagulated blood, can help in the diag- nosis of EDTA-PTCP.EDTA-PTCP occurs at a frequency of approximately 0.1% in the general population and 0.15% in hospitalized patients. According to literature data, EDTA-PTCP in the neonate due to mother has been reported only in few cases.Aim: We report on a case of EDTA-dependent PTCP in a neonate due to transplacental transfer of maternal EDTA-autoantibodies of IgG class. Case Report: A female newborn, birth weight 3250 g, born from first uncomplicated pregnancy to a healthy 23-year-old mother in 39th week of gestation. Mild throm- bocytopenia (82 to 100 9 109/L) was detected on the first day of the newborn’s life on routine laboratory checkup. Other laboratory findings were normal. No signs of hemorrhage were present. On day 3, platelet count dropped to 64 9 109/L and the newborn was transferred to the Neonatology Ward to investigate the etiology of thrombocytopenia. Upon excluding perinatal infection and congenital malforma- tions, serology of alloimmune neonatal thrombocytopenia was indicated. Serologic screening of maternal and neonatal EDTA anticoagulated blood samples using direct and indirect immunofluorescence method for antiplatelet antibodies (manual PSIFT) was positive. Serology of the maternal and neonatal sera for specific antiplatelet al- loantibodies (anti-HPA) by using the monoclonal antibody immobilization of platelet antigens (MAIPA) assay was negative. HPA (1–15) genotyping of the mother and the neonate showed no incompatibility. As direct manual IF test of maternal and neona- tal platelets showed platelet aggregates, blood smear from EDTA anticoagulated blood sample was done, along with CBC on hematology analyzer. Laboratory screen- ing for EDTA-PTCP was positive. Recollection of the maternal and neonatal blood samples using sodium citrate anticoagulant confirmed the diagnosis. Platelet count in newborn’s EDTA blood was 101 9 109/L and in citrate blood 695 9 109/L. Plate- let count in mother’s EDTA blood was 133 9 109/L and in citrate blood 369 9 109/ L. In leukocyte histogram provided by automated cell counter, platelet clumps of less than 35 fl appeared in EDTA blood of the mother and the neonate, but not in the citrate blood. On 3-week follow up, platelet count in newborn’s EDTA blood was 46 9 109/L and in citrate blood 382 9 109/L. On 6-week follow up, platelet count in newborn’s EDTA blood was normal (288 9 109/L). Conclusion: Although PTCP is a rare phenomenon, it should always be excluded in patients with newly detected thrombocytopenia to avoid erroneous interpretation of platelet and leukocyte count, unnecessary and false positive serology workup for antiplatelet antibodies and needless platelet transfusions.

peudothrombocytopenia ; maternal EDTA-autoantibodies of IgG class

DOI: 10.1111/vox.12429