Screening or prenatal diagnosis tests

Screening or prenatal diagnosis tests?

All mothers ask many questions in pregnancy. It’s normal. A very frequent question, for example, is the following: “How do I determine with certainty if my baby is suffering from chromosomal anomalies?”It is still:“ What a non -invasive prenatal test consists of?”Let’s see together the differences between the non -invasive prenatal tests and invasive tests.

Non -invasive prenatal screening tests usually combine biochemical analysis on maternal blood with ultrasound exams, and thus allow to calculate the probability that a fetal anomaly is present by comparing the results obtained with standard values. For this, these tests are called “probabilistic”: because they do not provide a diagnosis but calculate the percentage probability that the fetus is suffering from an anomaly such as a genetic disease or defects in the closure of the neural tube. These exams are completely safe And they do not put the health of mom and baby at risk.

Not all prenatal screening tests have the same percentages of reliability.

Exams such as the BI TEST, the TRI test and the test paintings analyze the values of some molecules in the maternal blood and also include an ultrasound examination, the nucal translucence, which allows you to carry out measurements on the fetus. The percentage of reliability of these exams reaches the85% 1 . Prenatal screening tests also include tests based on fetal DNA analysis. This type of test takes place only on a blood sample of the mother in which, through the latest generation machinery, the baby’s fragments of the DNA are identified and are analyzed. This test has a high reliability rate, Of 99.9% 2 .

The diagnostic tests include invasive types such as amniocentesis, villocentesis and cordocentesis. These tests directly analyze samples of liquid or tissue taken from the fetus or by the embryonic annexes and manage to identify with certainty the presence of anomalies, providing a diagnosis on the health of the child. These exams are carried out through withdrawal directly from the stomach of the pregnant woman.

With amniocentesis, an amniotic liquid sample is taken, with villocentesis a placenta biopsy is made while with the cordocentesis a blood sample is taken from the child’s umbilical cord. Diagnostic tests, being invasive, present a probability of meeting abortion of 1%.

Usually it is the gynecologist who advises the pregnant woman to which screening or prenatal diagnosis test to undergo on the basis of his state of health and the possible presence of risk factors, such as advanced age or presence of genetic family anomalies.

If you want to have more information on the fetal DNA, discover the Aurora test by visiting the website and asking for advice from our experts.


  1. Medicine of the prenatal age: prevention, diagnosis and therapy of congenital defects and the main pregnant pathologies

By Antonio L. Borrelli, Domenico Arduini, Antonio Cardone, Valerio Ventrut