Non Invasive Prenatal Test (Harmony)
The non-invasive prenatal test (NIPT) is a relatively new method of screening for chromosome abnormalities and works because a tiny amount of the baby’s DNA crosses the placenta into the mother’s blood. So with just a normal blood sample from the mother, the baby’s DNA can be analysed directly and the relative amount of each chromosome assessed.
The commonest chromosome abnormality, Down’s syndrome, can be picked up with over 99% accuracy, but it must be stressed that the test is not diagnostic and that a low-risk result does not mean that there is absolutely no risk and a high-risk result will still need an invasive test, such as an amniocentesis, to provide certainty.
Different laboratories have given the test different brand names, so you may hear the test referred to as the Harmony™ Prenatal test, the Iona test or the Panorama test, but the concept behind these tests is the same. Beard Mill Clinic currently uses the Harmony™ Prenatal Test.
The NIPT has been developed specifically as a screening test for Down’s syndrome, but the same genetic sequencing techniques can be used to analyse two additional chromosomes – chromosome 18 and chromosome 13 – and the Harmony™ Prenatal Test will look at the risk of Edwards’ syndrome (where the baby has an extra copy of chromosome 18) and Patau’s syndrome (an extra copy of chromosome 13) too. If you want to know, the Harmony™ Prenatal Test will also accurately identify the baby’s gender, but this will not be disclosed if you don’t wish to find out.
The NIPT blood test can be done from 10 weeks onwards, but it is more accurate if there is more DNA, so it is better to wait until 11 weeks if you can. There is no upper limit to performing the test.
NIPT is still only available privately at the moment, but has been recognized by NICE as an effective way of screening and there are plans to bring it in on the NHS later in 2018 – but only as a second-line screening test. Everyone will still be offered nuchal translucency screening in the first instance, with just the high-risk patients being given the option of having NIPT as an alternative to an amniocentesis.
However at Beard Mill Clinic the test is available to anyone and is particularly useful for older mothers who are more anxious because of their age, or for those who have had normal first trimester screening already and have been given a result that they aren’t completely happy with – or for those who just simply need a bit more reassurance.
Reasons for having NIPT at Beard Mill Clinic, include:
A very detailed scan is included as part of the test. In theory, the NIPT is just a blood test and some Clinics offer it as this, with just a cursory scan. But at Beard Mill Clinic, we believe that the non-invasive prenatal test should always be done in combination with a thorough scan. The test can be used in multiple pregnancies, but not if one twin stopped developing at an early stage (a vanishing twin), so it is important to have a scan to check this.
A good 12-week scan will occasionally pick-up a severe structural abnormality, such as spina bifida or a heart problem, so it is important to look at the baby’s anatomy too. And most importantly, an increased nuchal translucency measurement is also a marker for a wide range of conditions other than Down’s syndrome. It is therefore essential that the NIPT results are always looked at in the context of the 12-week scan findings and never in isolation and it is essential not to miss out on this important scan.
And just occasionally, something may be seen on scan which would mean that it may be more appropriate to do an invasive test (such as an amniocentesis) instead of NIPT. Therefore a detailed scan at Beard Mill Clinic is still recommended to make sure that NIPT is the best test for you to have and that there are no other obvious abnormalities. The type of scan performed will always be appropriate for the stage you are at in the pregnancy and as detailed as possible.
The Beard Mill Clinic Package
If you decide early on in your pregnancy that you will have NIPT, Beard Mill Clinic offers a package of having the NIPT blood test, the normal blood test that is offered routinely as part of the nuchal scan and a dating scan all done at around 11 weeks. You would then come back at 12+ weeks for a much more detailed nuchal scan and to go through all the results.
The results are currently taking about 5 working days to come through. If you opt to have the package, the results will be given to you face-to-face at the 12 week scan. Otherwise you will be contacted (usually by phone) with the NIPT results as soon as they are available.
Anyone can choose to have NIPT and can contact Beard Mill Clinic directly. A referral from your GP is not required. It can be performed in all single and twin pregnancies, including those conceived by IVF, even if donor eggs are used. The only exceptions are if the mother herself has an unusual chromosome rearrangement or if there has been a vanishing twin (see above).
Referral For Further Tests If Necessary
In most cases the anomaly scan provides parents with reassurance that their baby seems to be developing normally. But occasionally a major abnormality will be detected and further investigations may be required. In this instance Victoria will give you as much information as possible to help you understand potential problems and will arrange a referral directly back to your NHS consultant and will liaise with them to ensure the continuity of your family’s care.