The TN or Nuchal Translucency is a measure that is mainly used to verify the risks of the baby having Down's syndrome, among other malformations and genetic diseases. When the value of nuchal translucency is greater than 2.5 mm, means a higher likelihood of Down Syndrome.
In these cases, when the nuchal translucency is increased, it is recommended to make an examination called amniocentesis, which allows you to analyze the baby's chromosomes and accurately detect Down syndrome and other chromosomal abnormalities.
If the result of amniocentesis is normal, the possibility of Down's syndrome is ruled out, but the baby may still have other problems, such as cardiac malformations. When this happens, it is ultrasound by the 20th week of pregnancy and an exam called fetal echocardiography, to evaluate the heart of the fetus.
It is important to remember that the ultrasound examination is not able to diagnose Down Syndrome and is only used to calculate the risks. This means that a test considered normal (nuchal translucency less than 2.5 mm) does not guarantee that the baby does not have Down Syndrome, only indicates that the risk is low. The same happens when the nuchal translucency is increased. The risk of Down's syndrome is high, but the baby can be born without the disease.