Non-Invasive Prenatal Test:
To be 99.5% sure about Down’s syndrome, a new testing option called NIPT is available.
NIPT (non-invasive prenatal test) assesses fetal DNA from sample taken from the mother and is available in King’s College Hospital. It can be done throughout the pregnancy and requires a simple blood test taken from 10 weeks gestation.
This test should always be preceded with an ultrasound for checking fetal viability and gestation.
The results are available in 10 days and the test is now done in Australia. The test screens for:
The non-invasive prenatal test (NIPT) has been available in King’s College Hospital and is a test by which fetal DNA can be assessed from a blood sample taken from the mother. It requires a simple maternal blood test taken from 10 weeks gestation, but can also be done at any time throughout the pregnancy.
The NIPT should always be preceded by an ultrasound to check fetal gestation and viability.
• Trisomy 21 (Down syndrome) – 99.5% accurate and is the most accurate screening test for this anomaly.
• Trisomy 18 (Edwards syndrome) – 97% accurate
• Trisomy 13 (Patau syndrome) – 94% accurate
• Sex chromosomes – 95% accurate
• Triploidy – accuracy not documented
The accuracy of the test is reduced when the patients are:
– insulin dependent diabetics
– have high BMI
– are less than 10 weeks gestation
The chances of aneuploidy increase by a factor of 9 if the NIPT fails, therefore, patients with twice failed NIPT must be counselled and also consider invasive testing.
The failure rate of NIPT is 8%
It should be kept in mind that NIPT does not replace Nuchal Translucency scan at 12-13 weeks, but it can be performed along with it.
12-13 weeks Nuchal Translucency screen is responsible for checking fetal structure (early morphology scan of fetus), chances of early onset pre-eclampsia can be diagnosed, premature delivery, and low birth weight.