Amniocentesis is an optional part of pregnancy screening. The aim of the procedure is to check for abnormalities and malformations in the unborn child.
Below you will find further information and selected specialists for an amniocentesis.
There are various forms of prenatal diagnostics. The procedures all aim to monitor the development of a foetus and examine it for possible diseases. Some procedures assess various risks purely mathematically, e.g. first trimester screening. Others use tissue cells from the unborn child for examination (invasive diagnostics).
Amniocentesis, like chorionic villus sampling, is part of invasive, optional prenatal diagnostics.
Invasive diagnostic tests provide reliable information about any genetic disorders that may be present. In particular, chromosomal disorders such as Down's syndrome can be detected.
During amniocentesis, amniotic fluid is taken from the amniotic cavity. The amniotic fluid contains cells of fetal origin. These can be examined for genetic diseases.
The amniocentesis uses fluid from the amniotic sac of the pregnant woman © Sora_Kobayashi | AdobeStock
Amniocentesis can be performed from the 16th week of pregnancy. If clarification is required earlier in the pregnancy, a chorionic villus sampling is performed.
Amniocentesis is not part of routine prenatal care and is only carried out at the express request of the parents. As a rule, a prerequisite is a previous examination, such as first trimester screening or a cell-free DNA analysis with an abnormal result. The examination can also be useful in the case of certain diseases in the family.
Beforehand, the doctor must inform the parents about
in a detailed and easy-to-understand manner . As a rule, there is still no causal therapy for the disorders that can be detected by amniocentesis. Parents who are diagnosed with a child with a genetic disorder must therefore decide whether they wish to maintain the pregnancy.
Nevertheless, diagnostics can also be useful beyond the decision for or against pregnancy. It gives parents who decide to have the child time to prepare and inform themselves. In some cases, this also makes it possible to create better conditions for the child's optimal development. This is the case, for example, with hemophilia (bleeding disorder) or rare metabolic disorders.
Before the puncture, a thorough ultrasound examination is carried out. This is used to assess the fetal organs and the position of the placenta.
The puncture is performed transabdominally, i.e. via the abdominal wall. The doctor inserts a thin hollow needle into the amniotic cavity under ultrasound guidance and removes around 15 ml of amniotic fluid. The puncture only takes about a minute and is hardly painful.
The amniotic fluid is cultivated in the laboratory (the cells are multiplied further) and examined. The result is available after about 14 days. If necessary, a rapid test can be used in advance to
can be excluded or diagnosed. However, these are usually additional services that are subject to a charge.
After about 14 days, the cell culture can also be used for a molecular biological DNA analysis.
Important to know: In practice, the entire spectrum of possible genetic abnormalities is by no means tested for here. The doctors only look for specific genetic changes for which there are reasonable grounds for suspicion. These include, above all, fetal abnormalities and a history of stress.
The results of amniocentesis are generally very reliable. This applies in particular to common chromosomal disorders such as Down's syndrome.
In very rare cases, there are different cells with different genetic make-up in the fetus (the technical term for this is mosaicism). The further procedure must be discussed on a case-by-case basis.
The slightly increased risk of miscarriage is the greatest risk associated with any invasive diagnostic procedure. This has been significantly reduced in recent years. Current evaluations of large amounts of data have shown that the additional risk of miscarriage due to amniocentesis is around 0.1 percent. Of course, the experience of the examiner is of great importance here.
In rhesus-negative mothers, there is a risk of rhesus incompatibility (with a rhesus-positive child). In such a case, the mother forms antibodies against the fetus as soon as fetal blood enters her bloodstream, which may be the case when the biopsy needle is withdrawn.
Rhesus prophylaxis (a type of vaccination) carried out immediately after the amniocentesis prevents this immune reaction.
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