In pregnancies affected by fetal and neonatal alloimmune thrombocytopenia (FNAIT), an ultrasound is an effective way to detect FNAIT-related complications such as bleeding that could have life-threatening consequences for the fetus if left untreated. Due to a low platelet count or thrombocytopenia, the blood doesn’t clot, leading to uncontrolled bleeding and hemorrhage.
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.
How does an ultrasound work?
An ultrasound – also called sonography or sonogram – uses high frequency sound waves above the range of human hearing to create images of the organs, muscles, tissues and structures inside the body. Images can be displayed in 2D, 3D or 4D (3D in motion). In pregnancies affected by FNAIT, ultrasound is used to monitor the growth and development of the fetus, as well as the onset of any internal bleeding.
Learn more about FNAIT testing and diagnosis
What FNAIT complications can ultrasound detect?
ICH: The most dangerous complication in FNAIT for the fetus or newborn is intracranial hemorrhage (ICH). It occurs in one in 10,000 pregnancies, and early detection is key to the best outcomes. When it develops in utero, it is very hard to treat non-invasively and depending on the gestational age and viability of the fetus, the best option may be an emergency cesarean to initiate postnatal platelet transfusions.
Hemorrhage in other internal organs: Bleeding and hemorrhage can also occur in other internal organs, including the gastrointestinal tract, lungs or eyes. When bleeding is detected on an ultrasound during a FNAIT-affected pregnancy, the risk of hemorrhage is high as the blood doesn’t clot due to low platelet levels.
Isolated ventriculomegaly: Fetal ventriculomegaly is a defect of the central nervous system that sees an abnormal accumulation of cerebrospinal fluid in the brain. While the association between fetal isolated ventriculomegaly and FNAIT requires further study before it is confirmed, it is another complication that can be detected by ultrasound.
Fetal death: Unfortunately, FNAIT can be fatal for some fetuses, with miscarriage and fetal death more common. By ultrasound, the lack of fetal cardiac activity indicates that the fetus has died.
In pregnancies at risk of FNAIT, ultrasound is used to monitor the health of the fetus, ensure early diagnosis of the condition, monitor disease progression and ensure the best outcomes through timely treatment and early delivery, if necessary.
