Neonatal thrombocytopenia: incidence, serological and clinical observations.

Abstract

In this study, platelet counts were determined from the cord blood of consecutive 9142 newborns. Neonates with known autoimmune thrombocytopenia were not included. The platelet count < 100 x 10(9)/L was found in 64 newborns. In five of them, neonatal alloimmune thrombocytopenia (NAIT) was diagnosed. The overall incidence of neonatal thrombocytopenia was 0.7%, the incidence of NAIT was about 10 times less. Serological and clinical observations are summarized from 238 thrombocytopenic newborns (54 from the above group and 184 previously referred to serological investigations). All of the newborns were divided into two groups: NAIT (46 cases) and other thrombocytopenias (192 cases). Among platelet-specific antibodies in NAIT, 91.4% were anti-HPA-1a, the rest were anti-HPA-1b and anti-HPA-5b. In the majority of the cases, antibodies were detectable by the platelet suspension immunofluorescence test (PSIFT) and monoclonal antibody immobilization of platelet antigens (MAIPA) assay. In 19.6% cases, antibodies were detectable by MAIPA only. In 10.9% of these cases, antibodies were undetectable. Thrombocytopenia < 50 x 10(9)/L and hemorrhagic diathesis were more often observed in NAIT than in other thrombocytopenias, whereas associated disorders that could contribute to thrombocytopenia, here observed almost only in the latter group. We also report certain other observations, such as the presence of anti-HLA antibodies, a rise in the anti-HPA-1 a antibody titer after infection without pregnancy, and a higher incidence of petechiae in nonimmune thrombocytopenia as compared with the incidence of low platelet counts.