PLAYING IT SAFE WITH NIPT

NIPT screening in pregnancy is revolutionising healthcare for expectant parents. If you’ve not heard of it or aren’t sure what it entails, here’s what you need to know.

Finding out their baby has Down syndrome is a big shock for parents-to-be. For those who feel they will be unable to raise a child with special needs, it may even mean having to make the difficult decision to terminate the pregnancy. Dr Dalene Barnard, an obstetrician and gynaecologist at Mediclinic Kloof, recalls the case of a couple who faced that decision.

“Initially they thought they would terminate,” she says. “But they did a lot of research, spoke to parents of children with Down syndrome, visited a school for children with Down syndrome, and in the end, they decided to go ahead and have the baby. Now, they’re quite active and vocal around Down syndrome.”

What made the difference, says Dr Barnard, is that the couple had plenty of time to come to terms with the news, do their research and get ready for their baby’s arrival. “By the time the baby arrived, the whole family was prepared,” says Dr Barnard. The reason this was possible is that they had elected to have non-invasive prenatal testing (NIPT).

What is NIPT?

NIPT is a screening to identify whether your baby has a higher risk for developing certain chromosomal conditions. It works by analysing genetic material from the baby that is present in the mother’s bloodstream. NIPT was initially developed to screen for Down syndrome, but nowadays it can also be used to screen for trisomy 18 (Edwards syndrome) and trisomy 13 (Patau syndrome), as well as conditions affecting the sex chromosomes, explains Dr Narina du Plessis, a maternal foetal medicine specialist at Mediclinic Kloof.

Safer, sooner, more accurate

To understand what sets NIPT apart from other tests, you need to understand the difference between a screening test and a diagnostic test. “A screening test is one that tells you what the risk for a condition is; a diagnostic test gives you a 100% answer,” explains Dr Du Plessis. NIPT falls into that first category – it’s a screening test. “The only diagnostic (100%) prenatal tests are amniocentesis or chorionic villus sampling (CVS),” she continues. Both involve inserting a needle into the uterus to collect cells. “That’s invasive and we try to avoid invasive tests by improving the quality of our screening tests.”    

The other most common screening test is the comprehensive 12-week scan, which has an accuracy of 92-94%. But it requires special equipment and the medical provider performing it needs to have special training.

NIPT can be performed from as early as nine weeks and is 99% accurate in testing for Down syndrome. Because it involves a simple blood test, which then gets sent to the lab for analysis, no special training is required and there’s no specialised equipment involved. “There are different ways the blood sample can be analysed, but the Mediclinic Precise team makes use of Panorama NIPT, which is the best one – it’s the most accurate,” says Dr Barnard. Results typically take between seven days and two weeks.

NIPT isn’t standard

So why isn’t everyone having NIPT? For starters, “not everyone wants to know,” says Dr Barnard. “But in high-risk cases and cases where a Down syndrome baby would mean terminating because the parents can’t support the baby – or if the parents would keep the baby but want more time to prepare, I would recommend it.”

NIPT is also expensive, adds Dr Du Plessis. One of the reasons is that although it’s a simple blood test, the machine doing the test is very sophisticated. “Medical aids may cover NIPT in high-risk cases – such as if the mother is 39 or older or has had a baby with Down syndrome before. They may also consider paying for NIPT if we’ve done the first trimester screening (the more traditional way, which is 92-94% accurate) and the risk calculated falls into the high- or intermediate-risk categories. But where there are no obvious risk factors, patients will have to meet the expenses themselves.” 

Manage your expectations

While NIPT is the most accurate screening test available, Dr Barnard and Dr Du Plessis both emphasise that it’s still only a screening test. Anything it picks up will need to be confirmed with a diagnostic test – including the baby’s sex. “People have NIPT at nine weeks because they want to do a gender reveal, but they need to remember that’s not what the test was designed for and it’s not 100% guaranteed,” says Dr Du Plessis.

In addition, it can only pick up issues with a few chromosomes. “It can’t tell you anything about the structure of the baby – the chromosomes might be normal, but there may be an issue with the heart or hands or brain, for example, and there’s also a lot about your genetics that we don’t know,” she cautions.  

Every parent’s greatest wish is to have a healthy, happy baby. While NIPT may not give you all the answers, it can give you information you wouldn’t have had before – and that is always valuable.