NIPT (non-invasive prenatal testing) is a sophisticated screening test used to identify babies who are likely to be affected by the three most common chromosomal conditions affecting liveborn babies. These are trisomy 21 (Downs syndrome), trisomy 18 (Edwards syndrome) and trisomy 13 (Patau syndrome). NIPT is frequently referred to as the Harmony test, but it is important to understand that is simply a brand name and many others are available and equally effective. The same technology, but a different test, in different laboratories, can be used to check if a baby has a rhesus positive or rhesus negative blood type.
Screening in the NHS
In the NHS, women in England are offered an initial screening test for Downs syndrome (trisomy 21), Edwards syndrome (trisomy 18) and Patau’s syndrome (trisomy 13). The initial test is called the “combined test” (sometimes the quad test). This test has a high false positive rate (worrying people unnecessarily) whilst also missing a significant number of affected babies. Those who get a result suggesting a chance of 1 in 150 or greater will be offered additional testing. This is optional and your care provider should explain the combined test result to you and explore the options so that you can decide what is right for you.
All tests offered in pregnancy are optional, but this isn’t always made explicit. Declining testing is a valid choice and is the right thing for some people.
If you have a high chance combined test, from today, 1st June 2021, the NHS in England will offer you the choice of CVS or amniocentesis, or the newer blood test known as NIPT. Previously NIPT was not always available in the NHS. Invasive tests are diagnostic tests that can give a definite answer. However, many people are concerned about such tests because there is an increased chance of miscarriage following that type of test. Invasive tests are very useful if there is a need to investigate for chromosomal or genetic issues other than Downs, Edward or Patau syndromes.
So what is NIPT and is it right for you?
NIPT works in a totally different way to the combined or quad tests, but avoids the risks associated with invasive tests. It looks at fragments of your baby’s DNA in your blood. It can be used in pregnancies using donor egg or sperm, surrogate pregnancies and twin pregnancies. I am happy to discuss this with you, including whether (and why) you should also have the NHS standard combined test (the answer is probably yes!).
NIPT describes the type of test. There are many trade names for versions of these tests from different manufacturers. These include The SAFE Test, Iona, NIFTY, Harmony, Panorama, Verify, Serenity and more. These tests all use the same biological principles but have subtle differences in the technology used. Some of the tests offer to report on the chance of other conditions, but these tests are not yet verified to be reliable.
NIPT does NOT give a definite answer. It remains a screening test, meaning that it tells you how likely something is.
I use The SAFE Test This is a test which is processed in a dedicated laboratory at St George’s hospital, Tooting, which also processes samples from the NHS. This provides confidence regarding quality assurance and back up in the case of any issues arising. The reporting process is secure, using an electronic portal which tracks samples from the initial collection to the issue of the report to us. Other providers may send samples overseas of testing, or use a lab which does not have specialist clinician back up in the event of any questions of concerns.
How and when is it done?
You need to have had an ultrasound scan which confirms the gestational age. I do not undertake ultrasound scanning, but can provide information about how to arrange this if you have not already had one.
I visit you at home, although other arrangements can be made if this is not suitable for you. Appointments are offered throughout the week, including at evenings and weekends
A sample of the client’s blood is taken, usually from the arm, as a standard blood test. I then take or send the sample to the SAFE test laboratory at St Georges. They aim to issue a result within 5 working days from receipt of the sample.
NIPT can be done from 10 weeks gestation, although there is often a good argument to wait a little longer. This is discussed with clients on an individual basis. It can be done at any later stage of pregnancy right up to birth.
Why have the test with Walking With You?
If you want to discuss what is NIPT and is it right for you, whether in advance of having a combined test or once you have that result, I am always happy to discuss this with you. An initial phone conversation is free of charge and without obligation.
Many clinics offering this service simply take the blood sample, get you a result and then advise you to contact your NHS provider in the case of an unusual or “high chance” result. I provide a much more comprehensive service. We will explore your thoughts about what the test offers and might mean for you, ensuring that you understand the implications and limitations of testing. I aim to ensure that you have a balanced understanding of the conditions concerned, so that you can think carefully about how such difference might affect your family. I take the view that difference is not necessarily “a problem”, and indeed can make life richer and more interesting. For that reason, I prefer to talk about the chance of these conditions rather than the risk of them.
I report the results to you personally. In the case of an unusual or screen positive result, I have the skill, knowledge and experience to support you to work out “what next” and can make any necessary referrals for further care.
For those who continue their pregnancy knowing that their baby is almost certainly affected by one of these conditions, a comprehensive package of midwifery care and support is available through pregnancy, birth and beyond.
Support is also available for those who decide to end their pregnancy . Walking With You is a non-directive service, supporting choice and empowering families to make the decisions that are right for them.
Can NIPT tell the sex of my baby or test for other conditions?
I do not offer NIPT for sex identification. However, in many cases the lab will be able to give an indication of the sex of your baby if you wish to know. It must be remembered that this is a screening test and so the result is not absolutely certain and sex cannot always be identified.
I offer NIPT to find out the chance of your baby being affected by one of the three most common chromosomal conditions (Downs, Edwards and Patau syndrome). I do not offer testing for other much rarer chromosomal conditions because that testing has been found to be highly unreliable.
How much does NIPT cost?
A home visit (in Surrey or Sussex) and the test, including the initial consultation and reporting the result to you, costs £345.