What is Nuchal Fold Thickness
The Nuchal fold Thickness is a regular fold of skin found at the back of the fetal neck during the second trimester of pregnancy.
Increased nuchal fold thickness is a soft indicator associated with a variety of fetal abnormalities and is measured during a regular second-trimester ultrasound.
What does a thick nuchal fold mean?
A thickened nuchal fold in a second-trimester fetus has been shown in numerous studies to be a sonographic sign of high risk for Down syndrome.
149 of the 10,416 singleton pregnancies studied had an increased nuchal fold thickness. These studies included fetuses who were already at risk for aneuploidy due to maternal age or abnormal maternal serum alpha-fetoprotein (AFP) levels.
What is the normal range for nuchal fold thickness?
The measurement of nuchal translucency increases with gestational age which is the time between conception and delivery.
The greater the difference in measurement between babies of the same gestational age, the greater the risk for certain genetic disorders.
When your baby measures between 45mm (1.8in) and 84mm, an NT of less than 3.5mm is considered normal (3.3in). As said, your baby’s NT measurement will increase as they grow up to 14 weeks.
However, extra fluid is reabsorbed so even in a baby with a chromosome condition, a later NT scan can provide a normal measurement. This is why additional screening or testing is essential.
Can a baby with a normal nuchal fold have Down syndrome?
A normal amount of fluid in the back of the neck during ultrasound indicates that your baby does not have Down syndrome or another genetic disorder.
Even a normal NT measurement, however, must be considered in conjunction with the blood test result and other factors such as your age.
The sonographer will enter the NT measurement, blood test results, and other factors into a database to produce a more accurate estimate of the likelihood of Down’s syndrome.
Does a thick neck always mean Down syndrome?
The conclusions of an NT scan do not always indicate a fetal abnormality. Nuchal folds are common in healthy babies. A thick nuchal fold in a healthy baby can be caused by a number of factors including the position of the baby, inaccurate measurements, and typically the normal size differs for every baby.
The use of NT thickness as a screening tool for fetal abnormalities is still debatable.
What causes nuchal thickening?
Chromosomal abnormalities can cause nuchal thickening. Fetal movement failure is also likely to cause nuchal thickening.
Neuromuscular abnormalities can result in poor breathing and movement, both of which can lead to fluid accumulation. Intrathoracic and extrathoracic compressive syndromes are other causes.
How accurate is the nuchal fold test?
Nuchal fold tests can detect approximately 70% of trisomy 21, or Down syndrome, cases on their own. Many healthcare providers combine routine NT ultrasounds with blood tests.
When combined with first-trimester blood tests, the accuracy of predicting conditions rises to around 95%.
Using a blood test in conjunction with the nuchal translucency measurement provides more information about the patient’s baby’s chances of being born with a genetic disorder.