What is Nuchal Translucency scan?
The Nuchal Translucency scan gives us the values of nuchal fold thickness, which is the subcutaneous space behind the baby’s neck.
The normal NT value ranges from 1.6-2.4 mm in measurement. Any value above the normal limit is considered abnormal, suggesting a risk of fetal chromosomal abnormalities.
Why is the NT scan abnormal?
There are a few risk factors that facilitate abnormal NT scans.
Mostly the abnormality is due to fetal chromosomal abnormalities such as Down’s syndrome or Turner’s syndrome or Edwards syndrome, cardiovascular failure, and diaphragmatic hernia.
Increased age of the pregnant woman greater than 35 might be a predisposing factor.
A high NT doesn’t always indicate a chromosomal abnormality.
It is said that an NT scan has five percent false positives. Hydrops or lymphatic obstruction is the suggested cause of increased nuchal thickness.
What to do if the NT scan is not normal?
Do not panic if the NT scan results are abnormal. An abnormal NT scan does not always indicate the baby has a serious problem.
It signifies an increased risk of specific chromosomal abnormalities, such as Down syndrome. But additional tests are needed to confirm the diagnosis.
First, have a discussion with the doctor about your result. The doctor might lead you through the next procedures, including further screenings such as NIPT, and amniocentesis. or chorionic villus sampling (CVS)
These diagnostic procedures give additional details regarding the well-being of the child and help determine chromosomal abnormalities.
What is the high risk in an NT scan?
The risk rate of the NT scan is classified as low, intermediate, and high risk for precise evaluation by the obstetrician.
The high risk would be an NT of 6 mm, which shows a high probability of Down’s syndrome.
Yet, there can be the minimal possibility that it isn’t. The appearance of the nasal bone helps in detecting trisomy 21 with greater accuracy.
Hence, the absence of it also adds up to the increased risk of the NT scan.
Can a baby with Down syndrome have a normal nuchal translucency?
An NT value less than 2.9 mm is unlikely to have Down syndrome.
An increase in the NT value increases the risk of Down’s syndrome. Also, NT doesn’t provide us with exact results every time.
A normal NT might also rarely develop into a chromosomal abnormality, said that babies with Down’s syndrome have elevated hCG (Human Chorionic Gonadotropin) levels.
How common are abnormal NT scans?
Abnormal NT scans are mostly sporadic abnormalities, which means the abnormality has occurred through mutation and not an inheritance.
Increased NT is also seen in both 85% of chromosomally abnormal and 40% of chromosomally normal fetuses with exomphalos (a defect in the abdominal wall of the baby).
