[Preparation of maternal platelets collected by separator for use in fetal transfusion in a case of alloimmunization by anti-PLA1].

In one case of fetal thrombocytopenia due to maternal immunization against PLA1 fetal platelet antigen, maternal platelets were collected by automated plasmapheresis. The platelets were collected 24 hours before fetal transfusion at 28, 29, 31 and 36 weeks of gestation. The maternal platelets were irradiated and concentrated in a small volume (7.10(10) to 1,4.10(11) plts in less than 20 ml maternal plasma) a few hours before transfusion. When prepared as described, maximal and irreversible platelet aggregation is obtained with 20 microM of ADP and the pH is over 6, 5-6 hours after concentration. The amounts of transfused platelets were determined to increase theoretically fetal platelet counts over 200,000 plts/mm3. The fetal platelet counts, determined immediately after transfusion, showed an increase of 100,000 plts/mm3. Prenatal fetal transfusion of maternal platelets is available to avoid fetal bleeding during delivery, and during the early neonatal period.