A case of hemolytic disease of the fetus and newborn (HDFN) that was originally mistaken for neonatal alloimmune thrombocytopenia (NAIT) has been recently reported in the Asian Journal of Transfusion Science.
HDFN is caused by maternal antibodies targeting antigens in the membrane of fetal red blood cells (RBCS), destroying them and producing anemia. On the other hand, NAIT results from maternal antigen targeting platelets, leading to a low platelet count (thrombocytopenia).
Learn more about HDFN testing and diagnosis
Although thrombocytopenia in the context of HDFN is not rare, it is usually mild to moderate. Therefore, pregnancies complicated with severe fetal thrombocytopenia are more suggestive of NAIT.
“We are reporting an interesting case of HDFN‑associated thrombocytopenia mimicking NAIT in a baby born to a multiparous mother with multiple red cell antibodies,” the authors wrote.
The case involved a 34-year-old woman in her sixth pregnancy; she had four previous abortions and one birth. Her current pregnancy was complicated due to fluid buildup in fetal tissue (hydrops), and she was scheduled for a cesarean section at 31 weeks of gestation.
The mother had an O Rh negative blood type; further workup was positive for antibodies against four different RBC antigens.
She delivered a 1.75 kg baby; initial examination after delivery revealed red spots (petechiae) all over her body, suggestive of thrombocytopenia. Hemoglobin levels were close to normal, and her bilirubin levels were high.
She underwent phototherapy and a single exchange transfusion shortly after birth. After five days of phototherapy, bilirubin levels improved, but thrombocytopenia remained. The physicians made a provisional NAIT diagnosis, and the patient was transfused with 11 units of platelets plus intravenous immunoglobulin.
The patient showed continuous improvement during the next ten days. Testing for NAIT turned out negative, and the physicians concluded that the thrombocytopenia was due to a rare presentation of HDFN.
“Even though NAIT occurs in approximately [one] in 1500 live births, it has to be ruled out when a neonate has severe thrombocytopenia (<50 g/L), especially with bleeding manifestations,” the authors concluded.
