Nuchal Translucency
Our Nuchal Translucency screening program performed at the 11 to 14 week stage of pregnancy is fully accredited by the Foetal Medicine Foundation, giving our patients the best possible information available to ensure a healthy pregnancy and the developing baby's wellbeing.
What is Nuchal Translucency?
Every foetus has a layer of fluid along the back of their neck. The thickness of this fluid can be measured during an ultrasound scan at this early stage of pregnancy. This measurement can be used to determine whether the baby is at increased risk of major chromosomal abnormalities such as Down Syndrome.
What is a chromosomal abnormality?
Chromosomes contain the DNA that make up each person's genetic blueprint. Sometimes the number or the arrangement of these chromosomes are abnormal, and can result in various syndromes. The most common of these chromosomal abnormalities is Down Syndrome. A chromosome problem is possible in ANY pregnancy. Although the risk increases with age, the vast majority still occur under the age of 35, as this age group has 90% of all babies.
How do we assess the risk?
We use the Nuchal Translucency measurement obtained from the ultrasound scan, and combine it with other information such as the mother's age and the results of a simple blood test, to calculate a risk estimate. The detection rate for Down Syndrome is 85-90% when all this information is combined.
What is the blood test?
The blood test measures two chemicals, called free beta-hCG and PAPP-A, that are produced by the placenta that cross over into the mother's bloodstream. If there are chromosomal abnormalities, the levels of these chemicals can give us an indication of a potential problem.
How is the ultrasound done?
Ultrasound uses harmless high frequency inaudible sound waves to obtain images. Ultrasound waves are not dangerous or irritating for you or your baby. The ultrasound waves are transmitted and collected via a hand held probe which is moved over the abdomen. You will not feel any pain or discomfort.
Norwest Medical Imaging has the most advanced ultrasound equipment available in Australia. Our state-of-the-art-imaging ultrasound systems provide unprecedented image quality for medical diagnosis in obstetrics, with our sonographers and specialist radiologists highly trained and experienced in all facets of obstetric imaging.
Should I have this prenatal testing?
This is a personal and individual decision. The pregnant woman and her partner should have counseling with her doctor before undergoing the test, to gain a good understanding of the screening test, and to determine the implications of the test results. A screening test assesses risk - it does not definitively confirm or exclude the presence of an abnormality.
What does a low risk result mean?
A calculated risk of less than 1 in 300 suggests a low risk. As this is a screening test, it is important to realize that a LOW risk is not the same as NO risk however.
What does a high risk result mean?
A calculated risk greater than 1 in 300 is considered an increased risk, but once again this does not mean the baby will definitely have a chromosomal abnormality. The woman will need to discuss with her doctor whether to proceed on to have further prenatal investigations (such as amniocentesis or chorionic villus sampling).
What are the benefits of a Nuchal translucency scan?
- Highest detection rate of any non-invasive test for chromosomal abnormality
- Accurate dating of the pregnancy
- Diagnosis of twin or multiple pregnancy
- Diagnosis of early pregnancy failure
- Assessment of early structural development of the baby
- A further ultrasound at 18 to 20 weeks is recommended as this is the best time to detect the majority of structural defects in the baby
Preparation
To ensure clear images, you will be asked to attend with a full bladder. This is achieved by emptying your bladder 2 hours before your appointment and then immediately drinking 600ml of water. Do not empty your bladder again before the procedure. You may eat normally and take any necessary medication.
It is important that you are on time for your appointment to ensure there is sufficient time available to perform the procedure. Please remember to bring any relevant films and your referral to your appointment.
All Nuchal translucency examinations will be performed by one of our experienced sonographers. A single examination will take an average of 30 minutes.
Results
Nuchal translucency results will be ready in 48 hours.
Norwest Medical Imaging strongly advise that you return to your referring doctor, in order for your doctor to discuss your Nuchal Translucency report with you.
