This test has come into widespread clinical practice since 2011. There has been a tremendous uptake of this recently, mainly for aneuplodies, sex chromosomal abnormalities and more recently selected microdeletions.

There are several companies offering this test mostly international but local tests are also offered of late.

Most of the tests nowadays are done by a next generation sequencer and use massive parallel sequencing and various algorithms specific for the test to report on the presence or absence of these abnormalities. In this technique, there is no separation of fetal and maternal DNA done.

The other technique is using SNP’s and this does separate maternal and fetal DNA and hence deemed more accurate.

However, the positive predictive value (PPV) is not very accurate for trisomy 13 and it is low for Turner’s syndrome and the microdeletions.

Some of the shortcomings of this tests will be discussed and the factors limiting the accuracy of FFDNA.