Prenatal diagnostics includes various examinations during pregnancy that serve to detect problematic health conditions and developmental disorders of an unborn child at an early stage. It helps to identify genetic abnormalities, structural anomalies and other potential health problems, which enables better birth preparation and decision-making. You decide for yourself whether you want to take advantage of this offer. If so, we will inform you about the procedure, the possibilities and limitations of prenatal diagnostics and evaluate together with you which methods are suitable for you
As one of the largest perinatal centers in Switzerland, we offer a comprehensive range of prenatal diagnostics. We present the most important ones below. The most commonly used method of prenatal examination, ultrasound, is described in more detail elsewhere.
First trimester test (ETT)
The first trimester test (ETT) is a statistical method that is sometimes combined with ultrasound measurements of the child. This is used to calculate whether there is an increased risk of a genetic disease.
Certain hormones and proteins as well as an increased nuchal translucency of the child indicate an increased risk of the most common chromosomal disorder in humans, trisomy 21. The so-called first trimester test can be used to estimate the risk of trisomy 21 based on the mother’s age, blood tests and the nuchal translucency measurement. This will tell you how high the risk is that your child has trisomy 21. You decide at what risk you would like to have a chromosome analysis carried out on your child.
Non-invasive prenatal test (NIPT)
A non-invasive prenatal test (NIPT) is usually carried out from the 11th week of pregnancy. A small amount of blood is taken from the pregnant woman, usually between the 11th and 14th week of pregnancy. In addition to maternal DNA, this blood sample also contains small amounts of fetal DNA, which passes from the placenta into the mother’s blood. These DNA fragments are used for analysis. In recent years, non-invasive prenatal genetic testing (NIPT) has proven to be the best non-invasive method for ruling out trisomy 21, trisomy 18 and trisomy 13. The sensitivity and specificity for the detection of trisomy 21, trisomy 18 or trisomy 13 is higher compared to a first trimester test. Many other genetic diseases can also be detected. NIPT is also currently the best non-invasive method for excluding trisomy 21, trisomy 18 and trisomy 13 in twin pregnancies. There is no data available for higher-order multiple pregnancies.
A negative NIPT result means that there is no indication of a trisomy. However, a positive NIPT result does not necessarily mean that a trisomy is present. If a termination of the pregnancy is desired in the presence of a trisomy, a positive result must always be confirmed by means of invasive diagnostics – amniocentesis or chorionic villus sampling.
In principle, there are currently two different techniques on which the available tests are based:
- Single nucleotide polymorphism (SNP) method (Panorama test)
- Counting methods (all available tests except Panorama test)
Your doctor will decide which method is right for you.
If there are indications of malformations or significant growth disorders in the child, NIPT should not normally be carried out. Instead, a chorionic villus sampling or amniocentesis is recommended.
Since 2015, compulsory health insurance (basic insurance) has reimbursed NIPT for trisomy 21, 18 and 13 if a first trimester test has previously been carried out and the risk has been shown to be higher than 1:1,000. In all other cases, an NIPT is not covered by health insurance and costs between CHF 700 and CHF 1,000.
Placenta biopsy (chorionic villus sampling)
Chorionic villus sampling, also known as a placental biopsy, involves removing small pieces of tissue from the placenta with a needle and analyzing the DNA in these cells. Cells from the placenta are therefore examined, not directly from the child. This biopsy is possible from the 11th week of pregnancy and is carried out by a puncture through the abdominal wall of the pregnant woman, leaving the amniotic cavity untouched.
The risk of puncture-related miscarriage is less than 0.3% if the procedure is performed by an experienced specialist. The result is usually available after 10 to 14 days. It is also possible to analyze genes using the DNA from these cells, if there is a corresponding reason.
Since the cells of the placenta are examined, it is rare to find disorders that only affect the placenta and not the child. In such cases, an additional amniocentesis may be necessary.
Amniocentesis (amniotic fluid puncture)
During an amniocentesis, fetal cells are removed from the amniotic fluid. This examination is carried out from the 15th week of pregnancy. The risk of a puncture-related miscarriage is less than 0.3%. The result is usually available after 10 to 14 days.
In contrast to taking cells from the placenta, amniocentesis involves examining cells directly from the child, which makes the result relatively reliable. In addition, the DNA of these cells can be analyzed for genetic abnormalities if there is a corresponding indication.
A rapid test for the five most common chromosomal disorders can be carried out on request. This result is usually available within 24 hours. However, the costs of this additional examination are not covered by health insurance.
Frequently asked questions
Prenatal diagnostic tests provide information about various aspects of the unborn child’s health. These include genetic abnormalities such as trisomies (e.g. Down’s syndrome), structural malformations (e.g. heart defects or spina bifida), and infections that could be transmitted during pregnancy. In addition, prenatal tests can provide information about the developmental stage of the fetus and possible complications during pregnancy.
Even though prenatal diagnostics are very sophisticated today, there is no 100% guarantee that a child will be born healthy, even with normal prenatal examinations.
