What is the role of platelet dysfunction in neonatal alloimmune thrombocytopenia?

Updated: Aug 05, 2017
  • Author: Perumal Thiagarajan, MD; Chief Editor: Srikanth Nagalla, MBBS, MS, FACP  more...
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Answer

Answer

The prevalence of neonatal alloimmune thrombocytopenia is approximately one case in 200 term pregnancies; for clinically apparent disease, the prevalence is one case in 1500 term pregnancies. It is the most common cause of severe neonatal thrombocytopenia. [9]

This disorder occurs when maternal antibodies against fetal platelet antigens inherited from the father but absent in the mother cross the placenta and induce severe thrombocytopenia. Most cases of neonatal alloimmune thrombocytopenia are due to platelet antigens HPA-1a observed in mothers who are HPA-1b.

Less commonly, other platelet antigens, such as HPA-5b, are responsible for neonatal alloimmune thrombocytopenia. Thus, the pathophysiology of this disease is similar to that of the hemolytic disease of newborns. Unlike hemolytic disease, however, thrombocytopenia occurs during the first pregnancy in 50% of cases.

Typically, the diagnosis of neonatal alloimmune thrombocytopenia is considered when bleeding or severe thrombocytopenia occurs in a baby after an otherwise uncomplicated pregnancy. The affected infant may have intracranial hemorrhage, and the disorder is associated with a relatively high mortality rate. The platelet count should be checked immediately after delivery and 24 hours later as it continues to fall.


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