The most serious complication of fetal and neonatal alloimmune thrombocytopenia (FNAIT) is intracranial hemorrhage (ICH). It occurs in 7% to 26% of cases of FNAIT and can cause permanent brain damage or potentially death of the fetus or newborn. Early diagnosis and treatment of FNAIT is essential to avoiding the onset of ICH and ensuring the best outcomes for the baby.
What is FNAIT?
Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a rare but serious condition that affects 0.1% of pregnancies in which a pregnant mother’s immune system produces antibodies against the platelets of her fetus. This occurs when a fetus inherits platelet antigens from the father that are not compatible with the mother, typically involving a protein called human platelet antigen (HPA). The mother’s immune system recognizes the fetal platelets as foreign, attacking and destroying them, leading to low platelet levels (thrombocytopenia) in the fetus or newborn.
What is ICH?
In pregnancies affected by FNAIT, maternal antibodies attack the fetus’s blood platelets, leading the fetus to develop thrombocytopenia or a low blood platelet count. This stops the blood from clotting, leading to uncontrolled bleeding or hemorrhage. Hemorrhage can occur in the brain, gastrointestinal tract, lungs or eyes.
Hemorrhage in the brain is called intracranial hemorrhage (ICH) and it can be diagnosed during pregnancy via ultrasound. As a result of thrombocytopenia blood vessels become more fragile and prone to rupture. When they rupture, the blood doesn’t clot and instead it accumulates in the brain tissue. The severity of ICH depends on the location of the hemorrhage and the gestational age of the fetus.
Learn more about FNAIT causes and risk factors
In pregnant women with a history of FNAIT-affected pregnancies, preventative antenatal treatment via intravenous immunoglobulin (IVIG) plus corticosteroids can help delay or even avoid the occurrence of ICH.
ICH cannot be effectively treated in utero, but fetal platelet transfusions can help stabilize platelet levels and prevent further bleeding. IVIG can also help suppress the maternal antibodies, slowing their destruction of the fetus’s blood platelets.
Long-term consequences of ICH
If an ICH is not urgently treated it can result in neurological abnormalities, developmental delays, intellectual disabilities, seizures, cerebral palsy, deafness, impaired motor skills and delayed speech and language skills. In the most severe cases, it can lead to fetal or neonatal death.
ICH in an infant post-delivery
In most cases of fetal ICH, the pregnancy ends early with an emergency cesarean. This is to remove the fetus from the continued toxicity of maternal antibodies and to proactively treat the hemorrhage.
In some cases, ICH occurs late in pregnancy or during labor and delivery and is only diagnosed post-delivery.
Symptoms of FNAIT post-delivery may include, bruising, a pinpoint rash called petechiae and purpura, bleeding and a low platelet count. Once FNAIT is suspected it must be urgently treated with a platelet transfusion. An ICH may be diagnosed if the newborn shows symptoms of anemia, seizures, extreme sleepiness, apnea and has difficulty feeding. An ICH will be diagnosed using a cranial ultrasound.
A platelet transfusion will increase the baby’s blood platelet count, which will in turn help stop bleeding. The impact of the ICH and any long-term neurodevelopmental damage will be assessed on an ongoing basis.
