La translucenza nucale it is an examination that takes place with ultrasound that serves to establish a percentage of probability that the fetus is affected by Down syndrome.
It is not a genetic test and it does not analyze amniotic fluid, as amniocentesis does, therefore it is not a diagnostic test. It is only used to calculate the probability that the child has Down syndrome and in the event of a positive result, the expectant mother is advised to undergo theamniocentesis.20 PHOTOS
Ultrasound during pregnancy: what do you see?
During the nine months of pregnancy, the expectant mother will have to undergo various ultrasound scans. Here's what you will be able to see
Nuchal transulcence when doing
This examination is carried out by twelfth to thirteenth week of pregnancy. The nuchal transulcence created by the greater liquid present between the skin of the nape of the fetus and the underlying membranes at the level of the neck is examined under ultrasound. Its increase in thickness (which indicates the positivity of the test) determines an increased probability of resorting to a subsequent invasive investigation such as amniocentesis or CVS.
Nuchal translucency how it is done
The pregnant woman must be aware that nuchal translucency it is a non-invasive examination which makes use of a good ultrasound to calculate the thickness of the aforementioned liquid, the presence of cardiac anomalies, as well as to view the formation of the nasal septum which represents another indicator of greater risk that the child has Down syndrome: this chromosomal anomaly, in fact, delays the growth of the nasal septum (60% of children with this syndrome do not have the nasal septum visible on ultrasound).
This ultrasound examination however, it does not determine the certainty of expecting a child with chromosomal abnormalities or not. It is a screening carried out on the basis of probability calculations that take into account the age of the mother, the maternal origin and the presence or absence of familial chromosomal syndromes.
If the nuchal translucency is increased but the fruit of conception does not necessarily have any anomalies, women can undergo invasive screening (amniocentesis or CVS) for free for the control of the child's karyotype.Read also: Indipensable ultrasound in pregnancy
As far as the minor presence of this liquid is concerned, it is a probabilistic sign of fetal health which in any case does not exclude a priori that a chromosomal or genetic anomaly may be present. Everything is based on mathematical calculations of probability, and this examination is intended to guide the pregnant woman in the choice of more invasive but absolutely certain future investigations.
Nuclear translucency has a probability of certainty equal to 75-80%, and the risk of having a Down child is defined as high if it equals or exceeds one child in 250 children.
This screening can be done alone or combined with maternal biochemical analyzes via the bi-test or the tri-test