The fetal and neonatal consequences of maternal alloimmune thrombocytopenia.

Alloimmune thrombocytopenia is a relatively common and under-recognized entity. Prospective screening studies have suggested that at least 1 in every 1000 babies will be affected. While the severity of prospectively identified neonates is not as great as those 'routinely' identified as newborns, the incidence of intracranial haemorrhage in the fetus and neonate is the highest for any immune thrombocytopenia. Diagnosis is complex for the laboratory in view of the large number of platelet antigens and the importance of having sufficient numbers of typed controls. The importance of identifying the affected newborn extends to the likely need for antenatal management of the subsequent affected fetus. Studies to determine the optimal approach to this problem are ongoing. Ideally, prenatal screening of all pregnant women could be performed but this is not currently in practice.