Contents
What is prenatal diagnosis?
All pregnant women have access to prenatal screening (the three ultrasounds + the second trimester blood test). If screening shows that there is a risk of malformation or abnormality for the baby, further research is carried out by performing a prenatal diagnosis. It allows to notice or exclude the certain presence of a fetal anomaly or a disease. Depending on the results, a prognosis is proposed which can lead to a medical termination of pregnancy or to an operation on the baby at birth.
Who can benefit from prenatal diagnosis?
All women who are at risk of giving birth to a baby with a defect.
In this case, they are first offered a medical consultation for genetic counseling. During this interview, we explain to future parents the risks of diagnostic examinations and the impact of the malformation on the life of the baby.
Prenatal diagnosis: what are the risks?
There are different techniques, including non-invasive methods (without risk to the mother and fetus such as ultrasound) and invasive methods (amniocentesis, for example). These can cause contractions or even infections and are therefore not trivial. They are normally only done if there are strong warning signs of fetal damage.
Is prenatal diagnosis reimbursed?
The DPN is reimbursed when it is medically prescribed. Thus, if you are 25 years old and you want to perform an amniocentesis just for fear of giving birth to a child with Down’s syndrome, you will not be able to claim reimbursement for an amniocentesis, for example.
Prenatal diagnosis for physical malformations
Ultrasound. In addition to the three screening ultrasounds, there are so-called “reference” sharp ultrasounds which make it possible to look for the presence of morphological abnormalities: limb, cardiac or renal malformations. 60% of medical terminations of pregnancy are decided following this examination.
Prenatal diagnosis for genetic abnormalities
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.
La biopsy de trophoblast. 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.
Cordocentesis. 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.