• NIPT means non-invasive pre natal test also called as cell free DNA test. This is a simple test to know about the baby’s risk of having chromosomal abnormality.

How the test is done?

• The test is done on mother’s blood. As only mother’s blood is taken poses no harm to the fetus hence this test is considered as non-invasive test.

What is cell free DNA?

• As some of you might know that the DNA is present inside the cells of the body. But the fetal DNA IS found freely floating in the maternal blood hence called cell free DNA. Placenta is the connection between mother and the fetus. The fetal DNA shed of into the maternal circulation through the placenta. And this fetal DNA then can be studied.

When can this test be performed?

• This test can be performed after 9 weeks, though the ideal time is after the NT scan that is after 11 to 13 weeks.

What disorders NIPT can detect?

• Each one of us has 23 pairs of chromosomes in a cell i.e. total 46 chromosomes. Out of 46 chromosomes one set of 23 chromosomes come from mother and one come from father. An addition or deletion of any of these chromosomes can result in various abnormalities. NIPT can detect trisomy 21(Down’s syndrome) with accuracy of 99%, trisomy 18(Edward’s syndrome)  and trisomy 13(Patau syndrome) with accuracy of 98%. And also it can detect sex chromosome abnormalities. There is ongoing research in this field and now it is possible to detect abnormalities of all 23 pairs of chromosomes.

Is NIPT confirmatory?

• No NIPT is not a confirmatory test. It is a screening test. Any report which comes as high risk has to be confirmed by invasive test (Amniocentesis/Chorionic villous sampling).

Sometimes result can come as inconclusive, what does it mean?

As NIPT detects cell free fetal DNA in maternal blood, it requires minimum fraction of fetal DNA circulating in mother’s blood. If the fraction of fetal DNA present in maternal blood is less than 4% then the NIPT test fails to give the result.