Nuchal Translucency Scan Sydney NSW
A first trimester chromosomal screening using a nuchal translucency scan is recommended for all pregnant women in the first trimester of pregnancy.
What is a nuchal translucency scan?
The nuchal translucency scan is a non-invasive ultrasound procedure usually performed on the abdomen area, although it may also be performed vaginally. It is performed to measure the amount of fluid present on your baby’s neck and determine if there is any excess fluid. This assessment is important as it allows the diagnosis of potential fetal complications including Down syndrome. If our specialists detect any abnormalities using our state-of-the-art ultrasound technology, we will notify you of the risks and discuss your options. Counselling and recommendations for non-invasive prenatal testing or definitive tests such as amniocentesis or CVS (invasive confirmation of chromosomal complications) can be offered.
When is it recommended and how is my risk factor calculated?
The nuchal translucency scan is recommended between 12 and 14 weeks of pregnancy as this is the stage of the pregnancy when the thickness of the nuchal translucency fluid layer is seen differently from chromosomally normal fetuses. At The Centre for Women’s Ultrasound we will perform a detailed high quality scan during your first trimester which will be followed by a serum screening (a nuchal translucency scan).
When determining your risk of chromosomal complications there are three main independent risk factors used in the assessment, including:
- The mother’s age
- The nuchal translucency thickness in the fetus and the presence of the nasal bone
- The mother’s serum level of beta-hCG and PAPP-A
An assessment of fetal heart including tricuspid regurgitance and blood flow in a fetal vessel-ductus venosus is also used in the decision-making.
How accurate is the nuchal translucency scan?
The combination of a nuchal translucency scan and maternal blood tests can detect 95% of Down syndrome pregnancies as well as a range of other chromosome and structural abnormalities.
As well as Down syndrome detection, a nuchal translucency scan may also detect other abnormalities including:
- Cardiac defects
- Genetic syndromes
- Other chromosomal abnormalities
What is the difference between a nuchal translucency scan and other diagnostic tests?
Non invasive prenatal testing (NIPT) is currently available from 10 weeks for testing of fetal chromosomal abnormalities such as Down syndrome (Trisomy 21), Trisomy 13 and 18.
The 12 weeks nuchal translucency scan is still recommended as it will check how the baby is forming structurally, as well as pick up other chromosomal anomalies not detected by the NIPT.
Other diagnostic tests are often invasive which can potentially increase your risk of miscarriage (although this increase is considered minimal). A nuchal translucency test can also not provide 100% accuracy, whereas other diagnostic tests, in some cases, can. Our specialists recommend either having a nuchal translucency (non-invasive) scan first, or NIPT followed by a first trimester morphology/nuchal translucency scan. If we believe further diagnosis or confirmation is necessary we may recommend a chorionic villus sampling (CVS) or amniocentesis test.
The Centre for Women’s Ultrasound is a centre for excellence when it comes to performing first trimester Down syndrome screening using Fetal Medicine Foundation software from London, UK.