Prenatal diagnostic

History and Science

Prenatal diagnostics began to develop in the second half of the last century when researchers were able to visualize chromosomes. Hereditary factors, also called genes, are located on the chromosomes. It has only been known since 1956 that humans have 23 pairs of chromosomes in every cell of their body.

As early as 1930, it was found that women who became pregnant over the age of 40 were slightly more likely to give birth to a child with what was then called "Mongolism."

In 1959, a doctor came up with the idea of examining the chromosomes of people with this problem and found that they had 47 chromosomes instead of 46. The small chromosome number 21 is present three times in these individuals.

Family History

If you have a family member in your immediate or extended family with a disability, a hereditary disease, or a malformation, and you therefore fear that your child's risk is increased, it is important that you visit a genetic counseling center before pregnancy, if possible, and get well-informed information from a specially trained specialist.

The Methods

Chorionic villi biopsy-CVS-(chorionic villi sampling) from 10 weeks of pregnancy

Two invasive examination procedures are available for diagnosis or to rule out changes in the genetic material of the fetus: the so-called amniocentesis and the chorionic villus sampling.

The fertilized egg produces both the cells from which the child is formed and those from which the placenta develops. In early development, this placental tissue is called the chorion. The chorionic cells contain the same chromosomes and genetic information as those of the future child. As a result, chromosomes and certain hereditary factors can be examined in this tissue.

The risk that CVS will cause an abortion is around 1%. The fact that CVS can be carried out a month earlier is perceived by many couples as an advantage over amniocentesis for psychological reasons.

The First Trimester Screening Test - 11-14 Weeks of Gestation

Another possible examination is the measurement of the so-called nuchal fold (NT, neck edema, nuchal translucency). It is a non-invasive prenatal medical examination method. The measurement must be taken exactly between the 11th and before the end of the 14th week of pregnancy.

The risk of a chromosomal change is calculated from the combination of the mother’s age, gestational age, the nuchal translucency measurement, her blood values (hormone beta-HCG and protein free PAPP-A), and trisomies in previous pregnancies.

The interaction of these three measurements reveals 90% of chromosomal disorders. In only 5 out of 100 cases you get a falsely abnormal result, which can then be further clarified with an amniotic fluid puncture.

Amniocentesis AC - From 15 Weeks of Pregnancy

...but the trend is towards 16-17 weeks of pregnancy.

The aim of amniocentesis is to obtain child cells from the amniotic fluid. These cells are then processed and examined for their chromosomes. In addition to the most common chromosomal abnormalities, such as Down syndrome and disorders of chromosomes 13 or 18, a variety of other diseases can now also be identified if you look specifically for them.

The AC Technique: First, ultrasound is used to find the largest amniotic fluid deposit. Under ultrasound guidance, this area is then punctured with a thin needle through the abdominal wall. Approximately 20 ml of amniotic fluid is then removed through the cannula, the needle is pulled out again, and the puncture site is then treated with a plaster.

The procedure only takes a few minutes. The risk of amniocentesis is the occurrence of contractions and/or bleeding.

Miscarriage occurs in less than 1% (1:100-1:500) of all amniocenteses. The result of the amniocentesis is only available 10-14 days after the puncture. You can often get a quick test result after just 24 hours (through fluorescence in situ hybridization analysis carried out at an additional cost).

The Following Can Be Clarified in Detail:

• Deviations from the normal number of chromosomes, which can, for example, indicate Down syndrome
• Evidence of a congenital metabolic abnormality
• Progressive muscular dystrophy
• Rule out a neural tube defect
• Fetal risk in the event of possible Rhesus factor incompatibility, lung maturity in the event of premature termination of the pregnancy