There is no standard prenatal testing program for Fetal and Neonatal Alloimmune Thrombocytopenia (FNAIT), which means that FNAIT is often not diagnosed until post-delivery when the baby presents with symptoms.
As a rare condition that is estimated to occur in one in 1500 pregnancies, it is not as widely known among healthcare professionals. Underdiagnosis and misdiagnosis can lead to life-threatening complications 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.
Recognizing early symptoms of FNAIT
FNAIT can occur in first pregnancies, and it can remain undetected during pregnancy unless a fetal hemorrhage is detected on an ultrasound. Immediate treatment by intravenous immunoglobulin has shown to reduce the risk of severe fetal thrombocytopenia occurring.
Following birth, newborns can present with a range of symptoms – some that are milder and less obviously associated with FNAIT than others. In some cases, there is little evidence.
- Poor feeding
- Fatigue
- A red or purple pinpoint rash, called petechiae
- Purple patches of skin discoloration, called purpura
- Large bruises, caused by bleeding, called ecchymosis
- Bleeding, that doesn’t clot
- Blood in the stool or vomit, due to bleeding in the gastrointestinal tract
- A bulge under the scalp, caused by blood, called cephalohematoma
- Bleeding on the brain, called intracranial hemorrhage (ICH)
- Low blood platelet count
Due to a lack of awareness, the symptoms of FNAIT such as bruising, may be incorrectly attributed to trauma during the delivery. If diagnosis is missed or delayed, it can have serious consequences for the newborn.
If these symptoms are detected in the newborn, the recommended approach is to proceed with an urgent platelet transfusion, without waiting for a confirmed diagnosis of FNAIT. Diagnostic tests can be carried out once the emergency has been addressed.
The risk of late diagnosis in FNAIT
Maternal antibodies can cross the placenta from as early as 14 weeks and attack the fetus’s platelets. The fetal platelets start to progressively break down, causing the blood to lose its ability to clot. This can lead to uncontrollable bleeding and life-threatening hemorrhages such as intracranial hemorrhages (ICH), the most severe complication of FNAIT in fetuses and newborns. Without timely treatment of FNAIT, up to 26% of babies with FNAIT will suffer from ICH. Permanent brain damage, cerebral palsy, seizures, hearing loss and learning difficulties and even death, are all possible if ICH is left untreated or treated too late.
Internal bleeding can also happen in the gastrointestinal tract, spinal cord, lungs and eyes, with long-term consequences such as blindness or disability.
While FNAIT can be mild and require little treatment, recognizing the symptoms and proactively treating them can be life-altering for the baby.
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