Umbilical cord puncture

The Umbilical cord puncture is an invasive examination method in prenatal diagnosis. A small amount of blood is taken from the umbilical cord of the unborn child. It is used to identify diseases and genetic defects in the child.

What is the umbilical cord puncture?

After taking the blood through the umbilical cord puncture (Chordocentesis) this can be examined for blood group incompatibility with the mother, metabolic disorders, toxoplasmosis or rubella. Toxoplasmosis is a cat disease that is normally completely harmless to humans and that can be transmitted to humans (zoonosis). Serious damage to the unborn child can only occur if the mother becomes ill for the first time in the first trimester of pregnancy.

If the mother fell ill earlier or was infected later, this is not dangerous for the unborn child. In addition, hereditary diseases and chromosome abnormalities can be searched for in the blood. If there is anemia, the unborn child can receive a blood transfusion through the umbilical cord. Umbilical cord puncture is also used to administer medication for infectious diseases. Hereditary diseases or chromosome abnormalities cannot be cured.

Function, effect & goals

At the beginning of the umbilical cord puncture, the doctor uses an ultrasound device to determine the exact position of the baby. Then he looks for an easily accessible place on the umbilical cord. This should be close to the mother cake. A very thin hollow needle is inserted into the umbilical cord through the mother's building ceiling and one to two mm of blood is drawn. This examination is completely painless for the baby. The mother usually does not need to be anesthetized for this either.

The umbilical cord puncture can be performed from the 18th week of pregnancy. This examination is advisable if the mother has abnormal blood values, previous ultrasound examinations have produced abnormal results or to confirm the results of an amniocentesis, a chorionic villus sampling (examination of the placenta) or an associated FISH test.

Chromosome deviations that can be detected by this examination are Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), Patau syndrome (trisomy 13) or Klinefelder syndrome. Edwards and Pätau syndromes lead to serious damage to the unborn child and to an extremely short life expectancy.

Klinefelder syndrome is a chromosomal abnormality that only occurs in male babies. Your set of chromosomes has one or more additional x chromosomes. Men who are affected by this chromosome abnormality are very feminine in appearance and usually sterile. This chromosome deviation has no further effects. Due to the risk of complications, the umbilical cord puncture should not be performed without compelling reason. Depending on what exactly is to be examined, the result of the examination is available after a few hours or within a few days. Determining genetic abnormalities takes longer than determining infection or anemia.

Risks, side effects & dangers

The most common side effect of umbilical cord puncture is contraction of the uterus. It feels like a stomach ache. In most cases, however, this is harmless and subsides again relatively quickly. Penetration of the needle can cause infection. Slight bleeding from the uterus and leakage of amniotic fluid are also possible. The uterus or the placenta can also be injured. If the child moves unexpectedly during the examination, it can easily be injured by the puncture needle.

Therefore, constant monitoring with the help of ultrasound during the examination is essential. The most serious complication that can occur is a miscarriage. The risk is between 1% and 3% and depends on both the skill and experience of the doctor and the age of the mother. If the unborn child is given a blood transfusion through the puncture needle, a so-called umbilical cord tamponade can occur. Here the blood is not introduced into the umbilical cord, but into the surrounding tissue. In this case, the child must be born immediately by caesarean section, as there is a risk of undersupply. The puncture also allows blood from the unborn child to enter the mother's bloodstream. In most cases this is not a problem.

This only becomes dangerous if there is a blood group incompatibility between mother and child, because the mother's bloodstream begins to form antibodies against the child's blood. These antibodies can cross the placental barrier relatively easily. They would cause considerable problems in the bloodstream of the unborn child and in extreme cases lead to permanent deformities or death. Therefore, in such a case, the mother is given a preventive drug. Due to the relatively high risk of miscarriage and the possibility of further complications, an umbilical cord puncture should only be performed if previous tests and examinations have shown a reasonable suspicion of an illness in the unborn child or a chromosome abnormality.

In these cases, too, the benefit and individual risk must be thoroughly clarified with the attending physician before the procedure. If a chromosome abnormality is suspected, it should be agreed with the partner in advance what should happen if the suspicion is confirmed. A cure is not possible in these cases. Depending on the type of trisomy, the child has a very limited lifespan after birth. Therefore, in these cases the question arises whether an abortion is an option and if so, in which cases? Special psychological counseling is offered for parents in this situation.