Prenatal screening tests to be done during pregnancy
Pregnant women need to take good care of themselves so that their baby is completely well during pregnancy. For this reason, they must undergo all routine checks and perform the prenatal screening tests, such as fetal DNA testing, or prenatal diagnostic tests, such as amniocentesis’amniocentesis.
Prenatal screening tests are noninvasive and can be performed at various periods of gestation. Are useful in determining the likelihood that the fetus may have any chromosomal abnormalities.
During the first trimester of pregnancy, pregnant women can have the Bi Test and nuchal translucency, which are performed at the same time. This is a screening examination that can be done between 11 a and 14 a week of pregnancy. Consists of a simple blood draw used to analyze the dosage of two proteins (Free Beta-HCG and PAPP-A), whose altered values may suggest the presence of abnormalities. This blood test is combined with the nuchal translucency, an ultrasound examination that is used to perform several measurements on the fetus. If the measurements are found to be out of standard parameters, it is important to perform further investigations with invasive diagnostic tests. The reliability rate of the Bi Test is85% 1 and it is important to note that it does not provide a diagnosis but a probability of risk for chromosomal abnormalities, such as Down syndrome.
The noninvasive prenatal testing of the fetal DNA Can be performed from the 10th week of pregnancy onward. It consists of a simple blood sample from the pregnant woman, which is analyzed using state-of-the-art machines capable of detecting fetal DNA fragments found in maternal blood. This is a non-invasive prenatal screening test that can boast a very high sensitivity in detecting major chromosomal abnormalities (trisomies 21,18,13), reaching 99,9% 2 .
The Tri Test is another prenatal screening test, which can be performed between 15 to 18 weeks of pregnancy. It is an examination that combines blood tests and ultrasound scanning. From the pregnant woman‘s blood sample, values of three substances are analyzed: alpha-fetoprotein, unconjugated estriol, and chorionic gonadotropin. Ultrasound is performed to better interpret the test results and to get a complete picture of the possible presence of defects such as spina bifida or chromosomal abnormalities such as Down syndrome. The Quadratic Testing is a variant of this test and consists of analyzing the pregnant woman’s blood sample and measuring the hormone inhibin A. These are probabilistic type tests with a reliability of 70%.
Prenatal screening tests are recommended for all pregnant women, but especially for those with risk factors, such as age over 35 or cases of genetic abnormalities in the family. If screening tests indicate the presence of chromosomal abnormalities in the fetus, it is essential to undergo invasive prenatal diagnostic tests to confirm the test results.
Ѐ it is always a good idea to consult with your gynecologist, who can advise which tests to perform to get all the information about your baby’s health.
For more information on the Aurora noninvasive prenatal test: www.testprenatalaurora.en
1. Prenatal medicine: Prevention, diagnosis and treatment of birth defects and major pregnancy diseases-Di Antonio L. Borrelli,Domenico Arduini,Antonio Cardone,Valerio Ventrut
2. Poster Illumina ISPD_2014 Rev A