#NIPT: Parts of the fetal DNA enter the mother’s blood circulation and are checked in non-invasive prenatal testing (NIPT). The origin of cffDNA – Cell free fetal DNA is from placental trophoblast cells, and after the sloughing of these cells, it enters the mother’s blood circulation and constitutes 3-13% of the total free DNA in the mother’s blood circulation. This test is a screening test and the result of this test is not diagnostic and only shows us the possibility of genetic disorders so that other interventional tests can be performed if needed.
Taking a blood sample for testing is just like taking a simple blood test. A sample of the mother’s blood is taken by syringe and evaluated for free fetal DNA (cfDNA). In this method, sampling of fetal villi or amniotic fluid is not done, and sampling is done only of the mother’s blood, so there is no possibility of miscarriage or damage to it. Considering that cffDNA cannot be detected in the mother’s blood more than 2 hours after delivery, previous pregnancies do not cause a disturbance in the test results.
After the results of the NIPT test are prepared, taking into account the results of this test and the examination of the ultrasound and fetal health test performed in the first trimester, the possibility of the need for more examinations and tests will be determined.
What disorders does this test identify and when can it be done?
This test is used to detect chromosomal abnormalities such as trisomy 21 (Down syndrome), trisomy 18 (Edward syndrome) and trisomy 13 (Pato syndrome). The NIPT test can be performed at any time after the 9th week of pregnancy. While, NT ultrasound (nuchal translucency screening) between 11 and 12 weeks, chorionic villus sampling (CVS) between 10 and 15 weeks, quad screening between 15 and 22 weeks and amniocentesis between 15 and 20 weeks are performed. will be
Test accuracy:
NIPT test has less false positive and false negative results than other screening tests. In this method, the free DNA of maternal origin (cfmDNA) is separated from the free DNA of fetal origin (cffDNA) in maternal circulation, so the sensitivity and specificity of this method for examining disorders of chromosomes 21, 18 and 13 reaches over 99%. It is also possible to study the gender of the fetus in this method.
To whom this test is recommended:
This test for high-risk pregnancies includes:
Mother age over 35 years
Abnormal ultrasound findings (increased NT)
Failure to perform routine screening tests until 22 weeks for any reason or the presence of an abnormal ultrasound finding from 22 weeks onwards
Abnormal results of serum screening test
Presence of aneuploidy history in the family (aneuploid pregnancy in the past) or parents carrying Robertsonian translocation (translocation of balance causing risk for trisomy 13 or 21)
Women who are very afraid of sampling diagnostic tests such as amniocentesis or CVS
Women who are not burdened with the risk of miscarriage by diagnostic tests,
Women who have a history of repeated abortions (three or more abortions under 20 weeks or fetal weight under 500 grams)
Women who have a history of water sac rupture
Women who have golden embryos (embryos formed after several years of infertility, old parents or as a result of IVF pregnancy)
This post is written by Hamedabdi09366119173