The amniocentesis makes it possible to identify and diagnose genetic and chromosomal anomalies and more particularly Down’s syndrome. The HAS recommends, however, when it is possible, the use of this examination and to favor a DNA test in the context of screening for Down’s syndrome. Find out in which cases this examination is practiced during pregnancy.
What is an amniocentesis?
(Update of April 22, 2022). Amniocentesis consists in puncturing amniotic fluid Using a fine needle through the abdominal and uterine wall as part of the screening for Down’s syndrome. But all future parents do not need to do this exam. The amniocentesis, which is carried out under permanent ultrasound control, can be indicated in certain situations of which here are the most frequent.
When to make an amniocentesis?
In general, amniocentesis is scheduled for third month of pregnancy Between 15 to 17 weeks of amenorrhea. If necessary, it is possible to practice an amniocentesis until the end of pregnancy.
In what cases do we practice an amniocentesis?
- The age of the future mother :: an age over 38 when tests reveal a high risk : From this age, the risk of Down’s syndrome is 1 in 500 pregnancies and from 40 years old it is 1 in 100 pregnancies.
- Family history. Amniocentesis is proposed when there are family history of hereditary disease (certain myopathies, cystic fibrosis, etc.), malformation or chromosomal anomaly such as Down’s syndrome, as well as when there is a personal history of children with a chromosomes or genetic disease, and a history of false strata. spontaneous.
- Toxoplasmosis. When an infection of the fetus is suspected (toxoplasmosis …).
- Blood test. When a blood test practiced in the future mother shows a suspicion of Down’s syndrome.
- Nucal clarity. When the measurement of nual clarity, that is to say the thickness of the nape of the fetus, made during the ultrasound of the first trimester is positive (wider than normal).
- Malformations or growth retardation. When one or more malformations or growth retardation are detected at ultrasound. Downy 21 does not only concern older women: all women are affected even if the risk increases with age.
It is the doctor who practices amniocentesis during an ultrasound which allows it to position the needle well and check the position of the baby. This exam, which lasts an average of ten minutes, consists of take up amniotic fluid through the abdominal and uterine wall. This liquid contains fetal cells which can then be analyzed in the laboratory in order to seek any anomalies. In addition, the needle, connected to a syringe is very fine and the act is not very painful, but it is possible to feel abdominal cramps during the examination.
What are the HAS recommendations?
The High Authority for Health wishes lower the number of amniocenses by 50% in order to reduce the risks linked to this examination while carrying out a earlier screening for Down’s syndrome. Considering amniocentesis as an invasive gesture and which is not without risks, She recommends the DNA test since May 2017. Thanks to a simple blood test during pregnancy, it allowsAnalyze baby’s DNA. HAS recommends proposing this DNA test “after combined screening in the 1st quarter (or failing this after screening by serum markers alone in the 2nd quarter), women whose women estimated risk level is between 1 in 1000 and 1 in 51 “. Effective at more than 99%, this non -invasive prenatal screening (DPNI) has been reimbursed by health insurance since January 18, 2019, as specified in HAS, amniocentesis is recommended in specific cases within the framework of screening for Down’s syndrome.::
- If the level of risk of Down’s syndrome is less than 1/1000, there is no need to continue screening
- If it is between 1/1000 and 1/51 : The future mother is offered the circulating free DNA test of Down’s syndrome;
- If it is greater than or equal to 1/50 : the realization of a fetal karyotype and therefore an amniocentesis is offered immediately, while leaving the possibility for women who wish to carry out a DNA test first.
The High Authority for Health also insists on the need for Check the quality of the Nucal clarity examinationthat is to say the measurement of the thickness of the nape of the fetus, made during the first ultrasound of the third month, at 12 weeks of amenorrhea. A later screening using the dosage of serum markers can be practiced during the second quarter in women who could not, for example, benefit from combined screening during the first quarter. This blood analysis of serum markers is performed during the second quarter, between 14th and 18th week of amenorrhea. It reveals the rates of three serum markers: the HCG (hormone secreted by the placenta), the non -conjugated estriol and the fetal protein alpha, produced by the fetus.
What are the risks of an amniocentesis?
The risks of amniocentesis are exceptional for the future mother (less than 1/10,000). There is no impact on the long -term development of the child. THE Risks of miscarriageswithin two weeks of amniocentesis, are relatively low, but not negligible. Even carried out in the best possible conditions, amniocentesis leads to false layers in 0.5% to 1% of cases for a baby and 3 and 4% for twins, especially within 8 to 10 days following. Although very rare, the risks of infection must be taken into account.
Amniocentesis: what management?
Amniocentesis is an examination reimbursed by the health insurance fund In women aged 38 or over, those who have personal or family history of genetic diseases and the risks of giving birth to a child with Down’s syndrome as well as a blood modification of the rate of markers associated with a slightly high clarity are found during the first ultrasound.
