Neonatal alloimmune thrombocytopenia (NAIT) refers to a disorder in which fetal platelets contain an antigen, inherited from the father, which the mother does not have. This leads to the mother producing antibodies against the fetal platelet antigen, causing fetal thrombocytopenia (low platelets), which can then lead to bleeding in the fetus or newborn. This is similar to Rh isoimmunization, but with platelet antigens instead of red blood cell antigens.
The most common platelet antigen implicated in NAIT is anti HPA-la antibodies produced by a woman who is HPA-la negative (i.e. she is HPA 1b/1b). Other less common antigens can cause NAIT as well.
Mothers with NAIT do not show symptoms and, unlike Rh-isoimmunization, can produce high levels of antibodies and have fetal thrombocytopenia during their first pregnancy. Currently, universal screening for platelet antigen status is not standard care. Therefore, most women with NAIT are discovered after they have either fetal hemorrhage (typically intracranial) or newborn thrombocytopenia.
Treatment of NAIT
Treatment of NAIT is complicated and there are no universally-accepted protocols. Treatment involves a combination of intravenous immunoglobulin (IVIG) and steroids provided to the mother during pregnancy, fetal blood sampling, and fetal platelet transfusions. The dose and frequency of these interventions are individualized based on the patient’s history.
Carnegie Imaging for Women blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!