Nuchal translucency scan test is a test to investigate some
chromosomal abnormalities that may be in the baby during pregnancy. According
to the results of Nuchal translucency scan, the risk of chromosomal anomalies
called trisomy 21 (down syndrome) and trisomy 18 (Edwards syndrome) in the baby
is investigated. These diseases are those with mental retardation and some
organ anomalies. That is why these tests are called intelligence tests, nuchal
translucency scan is not a test that measures the baby's intelligence level.
For Nuchal translucency scan, blood is drawn from the mother
between 11-14 weeks of gestation (same as in normal blood tests). In this
blood, β-hCG and PAPP-A levels are measured and the result is determined with
the help of a computer by formulating with the age and some other features of
the mother. This test is called nuchal translucency scan. If the baby's nuchal
thickness (NT) is added to this formula, the accuracy rate of the result
obtained is clearer, this test is called combined test. In other words, the
combined test is a test performed by combining the nuchal translucency scan
with the nuchal thickness. Nuchal translucency scan screening can detect 65% of
babies with down syndrome, while 85% can be detected with combined test.
Neither test can detect all babies with down syndrome, and some of the
pregnancies carrying babies with down syndrome will not have a high risk as a
result of these tests, it will be normal.
As a result of the nuchal translucency scan, it is not
possible to determine whether these chromosomal anomalies exist in the baby
precisely. The answer to the question is whether the risk of these anomalies is
higher than normal. If the risk is higher than normal, CVS or amniocentesis
methods are applied to get the answer to the question of whether there are
certain anomalies in the baby.
Risk
assessment according to the result of Nuchal translucency scan:
As a result of the Nuchal translucency scan, a high risk
limit of 1/270 is considered for Down's sensory. That is, if the result is
greater than 1/270 (eg 1/200), the risk of having Down syndrome in the baby is
higher than normal, but the baby may also be normal. CVS or amniocentesis
should be performed for definitive diagnosis.
As a result of the Nuchal translucency scan, the high risk
limit for Edwards syndrome (trisomy 18) is considered as 1/100. That is, if the
result is greater than 1/100 (eg 1/80), the baby has a higher risk of Edwards
syndrome, but the baby may also be normal. CVS or amniocentesis should be
performed for definitive diagnosis.
Nasal Bone
measurement:
It is more correct to define the nasal bone as absence,
because the presence or absence of bone is evaluated. There are some centers
that evaluate the ultrasound evaluation of nasal bone, namely nasal bone, by
combining nuchal translucency scan. Failure to see the nasal bone on ultrasound
increases the risk of trisomy. Because the nasal bone can be seen in 98% of
normal fetuses between 11-14 weeks, not only in 2%. Nasal bone cannot be seen
in 70% of fetuses with trisomy 21. Nasal bone is not seen in 50% of fetuses
with trisomy 18. Nasal bone is not seen in 30% of fetuses with trisomy 13.
- BIOPHYSIC PROFILE (BPP)
- INTELLIGENCE TEST IN PREGNANCY
- BIG BABY
- CELL FREE FETAL DNA ANALYSIS (cffDNA)
analysis in pregnancy
fethal nuchal thickness test
fethal test
nuchal translucency scan test
tests in pregnancy
