The term prenatal diagnostics covers examinations during pregnancy. They are used to detect risks for the pregnant woman and her unborn child at an early stage. Diagnostics are primarily carried out using ultrasound. In particularly suspicious cases, a diagnostic puncture (e.g. an amniocentesis) can be helpful for further clarification.
Below you will find further information and selected specialists for prenatal diagnostics.
Prenatal diagnostics involves the examination of an unborn child in the womb. It is used to detect various risks at an early stage.
Various examinations are possible, e.g.
Three ultrasound examinations are firmly anchored in maternity care. There are also other useful examinations.
First trimester screening is a diagnostic test used by many pregnant women.
Screening has several objectives:
During the ultrasound, the gynecologist measures the child from the crown of the head to the rump. In this way, he checks the growth of the unborn child and clarifies the gestational age. He checks the heart activity and examines whether organs such as the extremities or the heart of the fetus are correctly positioned and developed.
Even at this early stage, more than half of structural malformations can be visualized by experienced hands.
Ultrasound is a proven method for examining an unborn child in the womb © Peakstock | AdobeStock
The measurement of fetal nuchal translucency (NT) takes place in the period 11+0-13+6 weeks' gestation. It plays a central role in first trimester screening.
Basically, it is an accumulation of water under the skin in the neck area of a fetus. It is present in all fetuses and is not an abnormality. However, if the accumulation of water is thickened, the risk of fetal disease increases.
If the NT is enlarged, there is an increased probability of the presence of
However, it is never conclusive of a problem and requires further investigation. In combination with the mother's age and hormone values from the mother's blood, a statistical risk calculation can be made. If carried out carefully, this risk calculation can indicate the presence of a trisomy with 95% accuracy.
Normal findings of nuchal translucency in the 12+5th week of pregnancy
In recent years, additional blood tests using cell-free DNA have become established. These also allow an examination for trisomies 21, 13 and 18, as well as the sex chromosomes.
The detection rates for trisomies are slightly higher than with conventional first trimester screening (97-99%).
Here too, there are false-positive and false-negative test results. In addition, the test does not cover the complete spectrum of possible chromosomal disorders. Therefore, the test alone should not be regarded as a conclusive diagnosis. In combination with a qualified ultrasound, this test is a good diagnostic option.
The blood test is currently still associated with additional costs for the parents-to-be. Furthermore, in 2-3% of examinations, no result is obtained.
The diagnostic puncture of the early placenta, chorionic villus sampling, is used for the early detection of chromosomal abnormalities. The examination can also detect single-gene diseases, e.g. hereditary metabolic or muscle diseases known in the family. It takes place from the 11th week of pregnancy.
In this diagnostic procedure, the doctor inserts a fine hollow needle through the abdominal wall and the wall of the uterus of the pregnant woman. He uses this to remove cell tissue from the developing placenta. From this sample, fetal cells are extracted in the laboratory and examined for their chromosome set.
The result of the chorionic villus biopsy is reliable. Very rarely (<1%) there are findings (e.g. mosaics) that require a repeat puncture for definitive clarification.
In exceptional cases, the removal of the fetal cells can lead to contractions or amniotic fluid leakage and thus cause a miscarriage. In experienced hands, this risk is 0.2% and therefore within the range of the natural miscarriage rate.
Amniocentesis can be carried out from the 16th week of pregnancy. Here too, the doctor uses a hollow needle to take a sample.
Under ultrasound guidance, he guides the hollow needle into the amniotic sac, from which he extracts some amniotic fluid. The amniotic fluid contains cells from the unborn child, which are examined in the laboratory for abnormalities.
The risk of miscarriage in experienced hands is 0.1%.
With the help of umbilical cord puncture (chordocentesis), doctors can examine the blood of the unborn child.
The doctor inserts a fine hollow needle into the pregnant woman's abdomen and takes some blood from the umbilical cord vein. This examination is painless for the child. The exact composition of the blood is examined in the laboratory.
This diagnostic procedure is primarily used to detect
Furthermore, unclear chromosome findings after amniocentesis can be checked using umbilical cord puncture.
In one in a hundred women, a puncture of the umbilical cord can cause a miscarriage. For this reason, this diagnostic procedure should only be carried out if there is a concrete suspicion and by an experienced examiner.
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