Do you need non-invasive prenatal testing?

Posted on 11 February 2020

Prenatal testing give doctors a detailed picture of your developing baby.

Every prospective mom knows all about an ultrasound. These monthly scans – which may increase in frequency towards a baby’s expected delivery date – help your gynaecologist track the growth, position and general health of a developing foetus.

These routine scans can give you a close look at your growing child. But they don’t end there.

Prenatal testing is an important part of any pregnancy, says Dr Lou Pistorius, a specialist obstetrician, gynaecologist and perinatologist at Panorama Perinatology, a foetal assessment centre at Mediclinic Panorama, and while routine scans give your gynaecologist an essential window into what is happening inside the womb, it is important to understand there is a lot more to look for – and a lot more to see.

“Most of our patients are referred to us by their gynaecologists or general practitioners, and many of them are looking into issues that may have been picked up by an ultrasound,” he explains. “These are issues that need to be monitored or examined closely by a specialist.”

A perinatologist, or maternal-foetal medicine specialist, is an obstetrician with special training in complex or high-risk pregnancy care. This means they are experienced in managing both pre-existing health issues in expecting moms, and serious health issues that can arise in a developing baby.

“If a mom is known to have high blood pressure, for example, this could have a significant effect on the pregnancy and the health of the baby,” says Dr Pistorius. “This needs careful management, and we work together with the gynae to provide a detailed treatment plan.”

A maternal-foetal medicine specialist is also useful when routine ultrasound scans show something unusual or unexpected. “Many times, these turn out not to be serious, but if there is something wrong, you need a very detailed picture – and a very experienced eye to examine it.”

Panorama Perinatology conducts a foetal assessment scan at between 11 and 14 weeks to look for structural abnormalities and chromosomal markers that are visible in the 1st trimester; combining an examination of the nuchal translucency, nasal bone and facial profile with a detailed maternal history and biochemical screening, doctors will calculate your baby’s risk of developing the three most common chromosomal abnormalities: Down Syndrome, Edward Syndrome and Patau Syndrome.

Then, at 20 to 24 weeks of pregnancy, doctors will look at the foetal anatomy, including the baby’s heart and connecting blood vessels, as well as his or her growth patterns and amniotic fluid volume. They will examine your placental function and cervical length re-assess the risk of Down Syndrome. They can also look for early signs of spina bifida and twin-twin transfusion syndrome.

These tests give perinatal specialists a highly detailed picture of your pregnancy, and empower them to pick up warning signs of health issues that may develop later, even after birth. “If we see structural issues, we may be able to advise patients to deliver the baby in a hospital setting with a cardiologist or cardiothoracic surgeon present – in that way, we can help manage the effects of an abnormality.”

A range of further, follow-up tests provide even more information. Depending on your family history or the results of routine scans, for example, you may benefit from chorionic villus sampling (CVS), done to confirm or exclude possible abnormalities of the foetus.

Early signs of a chromosomal abnormality can be examined in even more detail by means of a follow-up non-invasive prenatal test known as a cell-free DNA test, also known as NIPT (non-invasive prenatal testing), which involves analysing a blood sample from the mom.

Deafness, blindness, neurological problems are common effects that can be noticed, if tested early.
These tests empower the patient and her doctor to understand a baby’s risk profile and act accordingly. “Whereas in the past we were able to see if a baby was missing large chunks of DNA, we can now see even the tiniest mutations – which can have significant effects on the health of your baby.”