Non-invasive prenatal testing is a technique used to detect chromosomal and genetic abnormalities in the foetus. It\u2019s particularly recommended to couples with a family history or high risk, although any pregnant woman can have it. It\u2019s performed on a blood sample, so it\u2019s not invasive for the foetus or mother and it\u2019s a highly sensitive test. \u00a0It can be performed from the tenth week of pregnancy and the results are ready one to three weeks later, depending on the lab.<\/p>\n
This test is similar to amniocentesis or chorionic villus sampling, which are invasive tests because it\u2019s necessary to take samples directly from the woman\u2019s uterus. However, although they have a very high rate of reliability (99%), if the result is positive for some chromosomal or genetic abnormality, it\u2019s recommendable to obtain confirmation by means of more conventional tests.<\/p>\n
The test is designed to detect the most common conditions: Down syndrome, Patau syndrome and Edwards syndrome. But it doesn\u2019t detect all possible abnormalities.<\/p>\n
It can\u2019t detect potential foetal malformations, so ultrasound scans are needed for this.<\/p>\n
It\u2019s only for single pregnancies, so this screening test is not available for multiple pregnancy.<\/p>\n
Is it reliable?<\/p>\n
There are different labs that perform this test and they all give similar results in terms of reliability. Recently they have started to include the detection of a greater number of conditions.<\/p>\n
In a small percentage of cases it\u2019s necessary to repeat the test due to lack of results. This is because no foetal cells were found in the mother\u2019s blood, which can happen when it\u2019s performed during the early weeks of pregnancy.<\/p>\n
Nowadays this test is not covered by the public healthcare system, so it\u2019s expensive, but when used in conjunction with prenatal screening in the first trimester, it\u2019s reliability is almost 100%. If the results are suspicious, your doctor will recommend a more invasive test to confirm them.<\/p>\n