Non-invasive prenatal testing
Non-invasive prenatal testing (NIPT) is a way of testing your unborn baby for a number of genetic disorders, done by – you guessed it – non-invasive means. Whereas traditional testing involves entering the uterus and opening the cervix, NIPT is performed by taking a sample of your blood and analysing your baby’s DNA.
Should I have NIPT?It was worth it for me. The NHS test told me I was “high risk” (mostly due to my age I think). My consultant recommended the Harmony test which came back as low risk and is more accurate than the NHS test.
NIPT isn’t available on the NHS yet, but is available through a number of private clinics. Any woman can get NIPT, but you might be particularly keen to access the test if you are in the high-risk pregnancy bracket. This includes older mothers, those who already have a child with a genetic disorder, or those with a family history of such.
The results of the test can be used to help you and your doctor decide on the best plan for you and your baby, including whether you should have further internal diagnostic tests.
How does it differ from standard prenatal testing?
NIPT is a screening test rather than diagnostic, so it can only tell you the likelihood of your baby having a disorder – it’s not conclusive, but does have a high accuracy rate, more so than the combined test. The NIPT is non-invasive, so there’s zero risk to you or your baby by taking it, and it can also be taken much earlier than standard prenatal testing.
What can I expect from the procedure?
NIPT is a fairly painless affair – you will be given a simple blood test by a doctor or medical technician, which is then sent away for testing at a laboratory where technicians will check the cell-free DNA, or cfDNA, in your blood for signs of abnormalities. When the results are back, your doctor is likely to present them with the results of your first ultrasound or nuchal scan if you have had one. If your NIPT comes back positive, your doctor may recommend you have amniocentesis or CVS to confirm the result, and to check for other problems NIPTs cannot detect.
What does it test for?
NIPT tests for the most common chromosomal disorders, including trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), and trisomy 13 (Patau syndrome). Depending on which company you use, some also screen for chromosomal conditions such as triploidy and microdeletion.
The test also determines your baby's gender and blood type much earlier than you would ordinarily be told.
When should I have NIPT?
You can have NIPT from nine or ten weeks into your pregnancy – this is much earlier than other prenatal tests, including nuchal translucency screening (11-12 weeks), CVS (10-12 weeks), quad screening (15-22 weeks) and amniocentesis (15-20 weeks).
How accurate is the NIPT test?
It’s impossible for any test to be 100% accurate, unfortunately – but NIPT does have a very high reliability rate. The NIFTY test claims to be 99.5% accurate in screening for Down, Edwards and Patau syndromes, whilst the Harmony test reports more than 99% accuracy for Down syndrome, 97% accuracy for Edwards syndrome and 94% accuracy for Patau syndrome.
If your NIPT is positive, it’s likely your doctor will recommend further testing to get a better understand of your baby’s condition.
Where is NIPT available?
NIPT is not currently available on the NHS, but you can pay to have the test at many private facilities across England, Wales, Scotland and Northern Ireland. There are various providers of NIPT tests – the market leaders in the UK are NIFTY and Harmony.
How much does NIPT cost?I had Harmony (on the NHS, only in my area) after a high risk combined screening test. If I hadn't been offered it I would've paid for it privately due to the risk of miscarriage from invasive tests like the amnio and CVS.
Costs for NIPT range from around £300 to £900, depending on what is included – most tests also include an ultrasound scan. Very occasionally (about 3% of the time) a test will be inconclusive due to a lack of cfDNA in the blood, and you’ll usually be offered a retest free of charge.
When will NIPT be available on the NHS?
NIPT has been approved by the government for induction into the NHS, and will be offered to all pregnant women as part of NHS maternity care from 2018.
When will I get the results?
The waiting time for results will vary by provider – it’s best to speak directly to your clinic. Generally speaking, NIFTY results are available 10 working days and Harmony results two weeks after your blood test is conducted.