How is the amniocentesis performed

Amniocentesis / amniotic fluid examination & chorionic villi - placenta biopsy

If there is an increased risk of a chromosomal disorder or syndromic disease, for example due to increased maternal age, a family history or an abnormal ultrasound finding, an amniotic fluid test can be used to definitively exclude or diagnose a suspected disease. This examination is an optional part of prenatal care. This means that the examination will be reimbursed by the statutory health insurance if the parents or mother decide to do so.
Amniocentesis is usually performed from the 16th week of pregnancy.

Before every diagnostic puncture, there is always a detailed explanation, which also addresses the consequences of a conspicuous finding. In the run-up to the investigation, counseling services can be used in order to be able to deal with the topic in detail.

Under ultrasound control, the doctor pierces the abdominal wall with a thin cannula and sucks off a few milliliters of amniotic fluid in which the child's cells swim. These cells are multiplied in the laboratory and the chromosomes they contain are examined for number and structure. A quick test gives indications of possible damage after just one or two days; the laboratory needs around two weeks for the final result.

The amniotic fluid collection usually takes 1-2 minutes. Most women do not find the needle sticking into the abdominal wall particularly painful - similar to the injection when taking a normal blood sample. In most cases, the injection site is not anesthetized.

The examination is not completely risk-free for mother and child and should be weighed up by the pregnant woman or the parents before they consent to the procedure. The doctor uses an ultrasound control to avoid injuring the unborn child with the needle. In about 0.1-0.2% of cases, following an amniotic fluid test, there is a miscarriage (which occurs more frequently in the early stages of pregnancy even without surgery). Amniocentesis also rarely causes bleeding in the uterus, amniotic fluid leakage or an infection. The uterus almost always responds to the procedure with contractions that quickly stop on their own. In any case, the pregnant woman should take it easy for a few days after the amniotic fluid test.

Chorionic villus sampling & placental biopsy

The chorionic villus sampling is possible earlier in pregnancy (12th to 14th week of pregnancy) than the amniocentesis. Similar to amniocentesis, chorionic villus sampling can identify certain genetic and syndromic diseases.

The doctor either uses a thin cannula through the abdominal wall to extract cells from the attachment of the later placenta. More rarely, the sample is obtained through a thin plastic tube through the vagina and the cervix.

The risk of miscarriage in an experienced hand is around 0.2%. Possible complications are slight bleeding and, very rarely, infections. After the procedure, the pregnant woman should rest for a few days.

In the placenta biopsy, in contrast to the chorionic villus sampling, cells are removed from the fully developed placenta. The examination is therefore carried out later in pregnancy than the chorionic villus sampling.