[Pregnancy monitoring and labor planning in PLA1-induced neonatal alloimmunothrombocytopenia].

Alloimmune thrombocytopenia in newborns may lead to severe bleeding. Most often this thrombocytopenia is caused by incompatibility in the PlA system (mother PlA1 negative, child PlA1 positive). If the mother produces antibodies against PlA1 which cross the placenta, they will then destroy the child's platelets. Recent investigations have shown a strong correlation between HLA-DR3 and production of antibody. Since no screening for such antibodies is performed during pregnancy the resulting thrombocytopenia in the newborn will always be a sudden event. The best therapy is transfusion of PlA1 negative platelets; if no PlA1 negative donor can be found (2.25% of all donors) platelet concentrates of the mother may be used. After diagnosis of PlA related thrombocytopenia the relatives of the mother should be tested for PlA for the following reasons: 1. to determine PlA1 negative relatives to be used as possible donors in future pregnancies, and 2. to detect PlA1 negative women of child bearing age. If pregnant these women should be HLA-DR typed and followed for anti PlA1 antibodies to estimate the risk for the child and to determine further procedures, for instance sectio caesarea to avoid intracranial bleeding during birth.