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‐la (PLAl) incompatibility. No circulating antibodies were detectable in untreated maternal serum, but an adsorption/elution technique enabled the demonstration of the platelet‐specific anti‐HPA‐la (anti‐PLAl) in maternal serum. Cordocentesis at 35 weeks of gestation revealed a fetal platelet count of 18 × 109/1. Intrauterine platelet transfusion with HPA‐Ia (PLAl)‐negative donor platelets was performed prior to cesarean section.