Non Invasive Pre-Natal Testing (NIPT)
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Non-invasive prenatal testing (NIPT) is a new approach to testing whether a baby may be affected by a chromosomedisorder. From a small sample of the mother’s blood, we are able to identify certain chromosomal conditions, such as Down syndrome. During pregnancy, some of the baby’s DNA circulates in the mother’s blood stream. DNA is the substance that our chromosomes are made of and contains all our genetic information. Usually, each human being has 46 chromosomes, arranged in 23 pairs. Occasionally, a baby is born with three copies of a particular chromosome, rather than two. This is known as a trisomy. The most common trisomies are Down syndrome, Edwards syndrome and Patau syndrome. By analyzing the baby’s DNA found in the mother’s blood, we can detect whether or not there are abnormalities in the baby’s chromosomes.
What is Non-Invasive Prenatal Test (NIPT)?
Non-invasive prenatal testing (NIPT) analyses foetal‘cell-free’ DNA circulating in the pregnant mother’s blood. Foetal cell-free DNA (cfDNA) results from the natural breakdown of foetal cells (presumed to be mostly placental) in the mother’scirculatory system. It clears from her system within hours of giving birth. People usually have 46 chromosomes in each cell, but occasionally, extra copies of chromosomes can be present, as is the case in Down syndrome. Down syndrome is caused by an extra copy of chromosome 21. That is why it is sometimes called trisomy 21.
How is NIPT done?
The test is performed on a sample of the mother’s blood. About 10mls of blood is taken from the arm- just like a normal blood test. The blood is then sent to the laboratory for testing.
How safe is NIPT?
As it is a simple blood test, NIPT carries no significant risk to you or your baby.
When is NIPT done?
From 10 weeks of pregnancy. Studies have shown that by 10 weeks there is adequate foetalcell free DNA present in the mother’s blood to conduct the test. The test is not recommendedbefore that period. Therefore, it is essential that you have had an ultrasound scan and know theduration of your pregnancy and whether you are having one baby, twins, or more. If you have already had a scan early on in yourpregnancy, then on the day of the test (from 10 weeks onwards), another scan will be performed to confirm foetal activity and heartbeat.
How accurate is NIPT?
NIPT for Down syndrome is more than 99% accurate. This means that the test detects more than 99 out of 100 cases of Down syndrome, so there is only a very small chance that the test will not detect an affected pregnancy. There is also a small chance that the test will incorrectly show that the baby has Down syndrome when it does not. This is known as a false positive result. Even though the test is highly accurate, there is still a very small chance (around 1 in 300) of an incorrect result. Therefore, if the result of your NIPT predicts that the baby has Down syndrome, you will be offered an invasive test to confirm the result.request an appointment