Neonatal Alloimmune Thrombocytopenia

Background: Neonatal alloimmune thrombocytopenia (NAIT) occurs when maternal-fetal platelet incompatibility leads to formation of maternal antibodies and results in fetal and neonatal thrombocytopenia. Despite being a rare condition, it is the most common cause of isolated thrombocytopenia in the healthy newborn. Most cases have a mild presentation, but some can present with intracranial hemorrhage (ICH).

Objective: To characterize NAIT cases in a level II hospital.

Methods: Retrospective review of the cases of NAIT between 2014 and 2018. Data analysis was performed using SPSS®.

Results: Ten newborns were included (seven males). All pregnancies were correctly monitored, and all diagnoses were made in the neonatal period. Thirty percent of cases were first pregnancies. Fifty percent were born by eutocic delivery and the rest by dystocic (80% by cesarean). Two patients were preterm. There were six cases of normal birth weight and four cases of low birth weight. The diagnosis of NAIT was suspected in seven cases in the first 24 hours of life, in two cases in the first 48 hours and in one case at 72 hours. Clinically, three cases manifested only with cutaneous hemorrhages, three had ICH, one had both cutaneous lesions and ICH, and three cases were asymptomatic. We recorded minimal platelet values ​​between 4000 and 78000/µL. Platelet transfusion was performed in four cases, immunoglobulin in two and corticoid therapy in one case. Human platelet-specific alloantigens (HPA) responsible for causing NAIT were identified in 8 cases, with type HPA-5b being the most frequent. All patients were followed up subsequently in consult.

Conclusion: Most of our cases had a favorable clinical evolution. ICH cases occurred with platelet counts less than 60.000/µL and two of these patients had other comorbidities. Follow-up is essential for all patients, since NAIT can cause severe complications and long-term disabilities, particularly in cases of ICH.