A non-invasive prenatal test (NIPT) is an advanced screening test using DNA in the mother's blood to estimate the risk of a fetus being affected by Down’s syndrome, Edwards' syndrome and Patau’s syndrome and some additional conditions. There are many different NIPTs on the market, but the majority will screen for these three syndromes along with some additional conditions such as sex chromosome and autosomal aneuploidies. Edwards’ and Patau’s syndrome are much rarer than Down’s syndrome but are very serious and many affected babies die before or soon after birth. Trisomies occur when three, instead of the usual two copies of a chromosome are present.
“Traditional” prenatal screening offered during the first trimester of pregnancy is currently called the Combined Test (CT) as it combines maternal age, an ultrasound scan to measure the nuchal translucency (NT), with a maternal blood test for serum markers. This is an ultrasound scan to measure the nuchal translucency (NT), combined with a blood test. This is less accurate than NIPT, detecting only about 80%–90% of babies with Down’s syndrome and present a 5% false positive (FP) rate [1, 2].
The IONA® test has a higher detection rate (>99%) than the Combined Test. The IONA® test is also better able to exclude false positives. False positives occur when the test reports the baby is at a high risk of having Down’s syndrome but is actually unaffected. The IONA® test is much better at ensuring the babies reported as high risk are truly high risk. This allows the clinician to only refer the mother for an invasive test when it is highly likely the baby is affected. This means fewer pregnant women will undergo unnecessary invasive follow-up procedures such as an amniocentesis or CVS which can be stressful, painful and may carry a small risk of miscarriage.