Amniocentesis. Performed between the 15th and 19th week of pregnancy, amniocentesis allows amniotic fluid to be collected with a fine needle, under ultrasound control. We can thus look for chromosomal abnormalities but also hereditary conditions. It is a technical examination and the risk of accidental termination of pregnancy approaches 1%. It is reserved for women over 38 years of age or whose pregnancy is considered at risk (family history, worrying screening, for example). It is by far the most widely used diagnostic technique: 10% of women in France use it.
See the topic “Amniocentesis, a key examination”
The trophoblaste biopsy. A thin tube is inserted through the cervix to where the chorionic villi of the trophoblast (the future placenta) are located. This gives access to the child’s DNA to identify possible chromosomal abnormalities. This test is performed between the 10th and 11th week of pregnancy and the risk of miscarriage is between 1 and 2%.
The maternal blood test. This is to look for fetal cells present in small quantities in the blood of the mother-to-be. With these cells, we can establish a “karyotype” (genetic map) of the baby to detect a possible chromosomal abnormality. This technique, still experimental, could in the future replace amniocentesis because it is without risk for the fetus.
The cordocentèse. This involves taking blood from the umbilical vein of the cord. Thanks to cordocentesis, a number of diseases are diagnosed, in particular of the skin, hemoglobin, rubella or toxoplasmosis. This sample takes place from the 21st week of pregnancy. However, there is a significant risk of fetal loss and doctors are more likely to perform amniocentesis.