Invasive tests: choriocentesis and amniocentesis
Choriocentesis and amniocentesis are the two most common tests of prenatal diagnosis, the main objective of which is to determine the state of health and level of development of the fetus by obtaining its biological material: cells or tissues. During these tests, the chromosomes of the fetus are analyzed to exclude chromosomal disorders such as Down syndrome.
Choriocentesis, in other words, the chorion biopsy, aimed to detect malformations in the fetus by obtaining cells from the future placenta. The chorion biopsy is performed between the 8th and 12th weeks of gestation by transabdominal puncture (through the anterior abdominal wall). The advantage of this diagnostic method is its high accuracy since 99% of genetic anomalies are detected.
Amniocentesis is the safest invasive method of prenatal diagnosis that involves puncturing and analyzing a small amount of amniotic fluid. In other words, amniocentesis is the analysis of the DNA of the fetus contained in the cells of the amniotic fluid. This test is performed between the 16th and 21st week of pregnancy.
It should be noted that invasive prenatal diagnosis is necessary if non-invasive techniques such as prenatal screening or ultrasound have detected an abnormality.