Diagnosis and management of foetal thrombocytopenia.

Platelet counts remain stable during intrauterine life (245 +/- 65 x 10(9)/litre, mean +/- SD). Before diagnosing thrombocytopenia (< 150 x 10(9)/litre), a foetal blood sample must be checked for contamination with amniotic fluid, since even slight contamination can activate coagulation and lead to a false positive result. In this paper, we review the major causes of thrombocytopenia and discuss their pathogenesis and management. Foetal thrombocytopenia can be caused by maternal complications (immune thrombocytopenic purpura, neonatal alloimmune thrombocytopenia, gestational thrombocytopenia, preeclampsia, alloimmune haemolytic disease) or infectious diseases (toxoplasmosis, cytomegalovirus, rubella) or be of true foetal origin (chromosomal abnormalities, malformations, congenital thrombocytopenia, intrauterine growth retardation.