Difficulties in the antenatal assessment of neonatal alloimmune thrombocytopenia

In this paper we present a patient with an initially questionable history of neonatal alloimmune thrombocytopenia (NAT) due to materno-fetal HPA-1a (PLA1) incompatibility. No circulating antibodies were detectable in untreated maternal serum, but an adsorption/elution technique enabled the demonstration of the platelet-specific anti-HPA-1a (anti-PLA1) in maternal serum. Cordocentesis at 35 weeks of gestation revealed a fetal platelet count of 18 x 10(9)/l. Intrauterine platelet transfusion with HPA-1a (PLA1)-negative donor platelets was performed prior to cesarean section.