Non-invasive prenatal testing (NIPT) is a prenatal screening test that looks to see if there is a low or high chance of your pregnancy having a chromosomal condition. Chromosomes are structures in our cells that contain DNA. Usually, we have 23 pairs of chromosomes. Changes to the number or structure of our chromosomes can affect our health and development.
Specialist Women's Ultrasound offers both Harmony™ NIPT and Percept ™ NIPT. Analysis is performed in Melbourne and most patients will receive their results within one week of sample collection.
The cost of Harmony NIPT is $460 and Percept NIPT is $495. The cost of Harmony NIPT or Percept NIPT includes pre-test genetic counselling; communication of the results to the patient and treating Doctor and post-test counselling in the event of a high-risk result. At the moment there are no Medicare or Private Health rebates available for this testing. Bloods can be collected at nearby pathology services following your appointment.
How do I arrange to have the non-invasive prenatal test (NIPT)?
Please call us on 03 9898 9055 to book a NIPT appointment with our Genetic Counsellor. Appointments are available on Mondays, Wednesdays, and Fridays. Our Genetic Counsellor will discuss the different testing options and help you make an informed decision about the test that is right for you.
What information can NIPT provide?
Harmony NIPT screens for Down syndrome (Trisomy 21) and Edward syndrome (Trisomy 18) and Patau syndrome (Trisomy 13). Harmony NIPT can also look at fetal sex and detect abnormal numbers of the sex chromosomes (including Turner syndrome, Kleinfelter’s syndrome, and other sex chromosome abnormalities). Screening for Di George Syndrome (22q11.2 deletion syndrome) is also available for an additional fee.
Percept NIPT screens for Down syndrome (Trisomy 21) and Edward syndrome (Trisomy 18) and Patau syndrome (Trisomy 13). It can also determine fetal sex and detect abnormal numbers of the sex chromosomes (including Turner syndrome, Kleinfelter’s syndrome and other sex chromosome abnormalities).
Percept NIPT also screens for rare trisomies (three copies of any chromosome other than 21,18,13, X or Y) and partial chromosome changes (deletions or duplications above 7Mb) for all 23 pairs of chromosomes. If a parent carries a balanced translocation Percept may be able to screen for unbalanced forms of that translocation from 11 weeks. Discussion with our genetic counsellor in consultation with the testing laboratory would be needed to ensure the translocation is suitable for Percept. A copy of parental karyotypes would need to be provided before your appointment.
When is NIPT performed?
We recommend testing from 10 weeks and 3 days to ensure there is enough fetal DNA in your blood to obtain a result. NIPT can be performed in single and multiple pregnancies. Triplet pregnancies can only be screened via Percept NIPT after 12 weeks gestation. What do my results mean? The results return as either high risk (high probability) or low risk (low probability). You will receive your results by phone as soon as they are available.
In the event of a high risk result your Doctor or our Genetic Counsellor will contact you and discuss the result. NIPT results are not diagnostic (i.e. Not 100% certain) and therefore further diagnostic testing will be recommended. Diagnostic testing during pregnancy is completely optional and involves testing by Chorionic Villus Sampling (CVS) or Amniocentesis. Diagnostic testing after birth is also available. Post-test counselling will be provided by our Genetic Counsellor to help you make an informed decision about your testing options.
What are the benefits of NIPT?
NIPT is considered the ‘gold standard’ in prenatal screening. It is a simple blood test with no risk of miscarriage. The test has a higher detection rate for Down syndrome compared to the 12 week nuchal translucency scan and first trimester combined screen. NIPT also has a lower false positive rate than the combined screen, meaning that fewer patients would be recommended to have CVS or amniocentesis to confirm a high-risk result.
What are the limitations of NIPT?
NIPT is a screening test which means that false positives and false negatives can occur. A low risk result does not completely exclude a chromosomal condition (although it does greatly reduce the risk). A high-risk result does not guarantee that baby has a particular condition. Very rarely false positives can occur. The positive predictive value (or chance that baby has a condition given a high-risk result) varies between conditions and tests. False positives may occur for a number of different biological and technical reasons. Your Genetic Counsellor will discuss with you about the specifics of each test. In the event of a high risk result we would recommend invasive diagnostic testing such as CVS and amniocentesis. There are no NIPT available which can screen for all chromosomal conditions. NIPT cannot screen for genetic conditions e.g. Cystic Fibrosis or Fragile X syndrome A small percentage of women will not get a result from NIPT, often because of low levels of fetal DNA in the blood. If this occurs repeat testing will be arranged. After two ‘no results’ the cost of the test is refunded and alternate testing will be discussed.
Who should have NIPT?
All women should be offered prenatal screening and NIPT is just one of the testing options available. NIPT may not be accessible for everyone due to the indication for testing, limitations of testing and for some the cost may be restrictive. This test is a screening test, not diagnostic, and is not able to provide a definite ‘yes or no’ result for Down syndrome or other chromosomal conditions.
NIPT after the First Trimester Combined Screen
Patients may be offered NIPT following the combined first trimester screening test (ultrasound and blood test), using the combined results to guide management and decisions about NIPT. The nuchal translucency ultrasound risk assessment is performed between 12-13 weeks and combined with a maternal serum screening blood test (best performed at 10 weeks). The combined screening result can be used to guide further management.
1. Greatly increased risk (risk greater than 1 in 50): offer CVS/amniocentesis. This is the risk range which has the highest chance of having a chromosome abnormality, Down syndrome or otherwise, many of which would not be detected through NIPT.
2. Increased risk (1 in 50 to 1 in 300 risk): offer CVS/amniocentesis or NIPT. This is the risk range where most of the false positive results of the first trimester screening test occur. CVS or amniocentesis would provide certainty about chromosome abnormalities but have a low risk of causing miscarriage. Patients who want to avoid this risk may opt for NIPT. If the NIPT result is high risk, then an amniocentesis would be recommended to confirm the diagnosis.
3. Low risk (1 in 300 to 1 in 1000 risk): offer NIPT. This is the low risk range where most of the false negative results from the first trimester screening test will occur (missed cases of Down syndrome). You may consider having NIPT to try to detect these cases.
4. Low risk (risk less than 1 in 1000): suggest no further testing. The chance of having a baby with Down syndrome after a result in this range is very low indeed.
Does NIPT replace the 12-13 week (nuchal translucency) ultrasound?
No. We still recommend having the 12-13 week (nuchal translucency) ultrasound. At the nuchal translucency ultrasound, it is estimated that approximately 50-60% of major structural abnormalities can be detected. If abnormalities are identified on this ultrasound further diagnostic testing may be recommended.
Will NIPT replace amniocentesis and CVS?
For most patients a low risk NIPT result is reassuring, and they will not go on to have an invasive test (CVS or amniocentesis). However, there is still a role for amniocentesis and CVS which includes confirmation of high-risk results, testing for familial conditions and testing after abnormalities have been identified on ultrasound. For further information please see CVS and amniocentesis.
How do I get further information about this test?
Please contact Specialist Women’s Ultrasound on 9898 9055 and ask to speak to our Genetic Counsellor for further information and discussion about this and other testing options for Down syndrome and chromosome abnormalities. All NIPT ordered through Specialist Women’s Ultrasound come with pre-test genetic counselling to help you make an informed decision about your pregnancy screening.
*The information above is general in nature and does not take into account your personal circumstances. Please speak to a Medical Practitioner regarding your own unique circumstances.