[FETAL/NEONATAL ALLOIMMUNE THROMBOCYTOPENIA (F/NAIT) - THE PREVALENCE VERSUS AWARENESS OF A LIFE-THREATENING CLINICAL CONDITION].

Aims: To determine the prevalence and incidence of HPA antigens and antibodies in the Israeli population and to evaluate the degree of awareness to F/NAIT in Israel.

Background: In fetal/neonatal alloimmune thrombocytopenia (F/NAIT) the fetus suffers from thrombocytopenia mediated by maternal IgG antibodies directed against fetal platelets leading to intracranial hemorrhage (ICH) in about 20% of cases. The antibodies are directed against Human Platelet Antigens (HPA). Diagnosis of F/NAIT is essential because thrombocytopenia may recur and worsen in subsequent pregnancies; hence awareness of F/NAIT is crucial.

Methods: We conducted a retrospective analysis of cases referred to the platelet immunology laboratory between the years 2011-2015 and medical records of newborns born at Rambam Medical Center during 2010-2015.

Results: Of the 322 cases studied, 175 (54.35%) had anti-platelet antibodies. The most common antibody was anti-HPA1a (41.85%) followed by anti-HPA5b (28.75%). The prevalence of HPA antigens was similar to that of the Caucasian population. About 80% of the cases were referred due to neonatal thrombocytopenia, found in a random blood count or after bleeding, and 13% of cases were referred due to suspected ICH during pregnancy. In only 22.6% of cases, the diagnosis was made immediately after birth, and 18.7% of the suspected cases were referred only during the subsequent pregnancy. About 84% of infants with severe thrombocytopenia were not referred to F/NAIT diagnosis.

Conclusions: The prevalence of platelet antigens in the Israeli population is similar to that of the Caucasian population. The paucity of referrals points to the need to establish diagnostic guidelines and raise awareness among caregivers.