What is first trimester screening?
First trimester screening is also called first trimester screening or first trimester test. It is a prenatal screening in the first trimester of pregnancy for genetic disorders in the child. However, screening only allows the calculation of a probability of genetic diseases, malformations or chromosomal abnormalities; it cannot detect them directly.
What is examined during first trimester screening?
During first trimester screening, the physician draws blood from the expectant mother and performs a high-resolution ultrasound examination on the unborn child:
Determination of blood values in the maternal serum (double test):
- PAPP-A: Pregnancy Associated Plasma Protein A (product of the placenta)
- ß-hCG: human chorionic gonadotropin (pregnancy hormone)
High-resolution ultrasound examination of the baby:
- fetal nuchal translucency (see below)
- length of the fetal nasal bone
- blood flow across the right heart valve
- venous blood flow
The result of the ultrasound examination (sonography) on the unborn child depends on the quality of the ultrasound machine and the experience and skills of the gynecologist. Information on qualified practices and physicians in your area can be obtained from the Berufsverband niedergelassener Pränatalmediziner e.V. (professional association of practicing prenatal physicians).
Taking into account the blood and ultrasound results as well as other risk factors (e.g. the mother’s age and nicotine consumption), a computer program uses a specific algorithm to calculate how high the risk is for a trisomy, another chromosomal anomaly, a heart defect or other malformations. The age of the mother is a very important influencing factor: the older the expectant mother, the higher the probability of chromosomal damage in the child.
False-positive results are quite common in first trimester screening. This means that a critical value is determined, which is then not confirmed in the subsequent tests.
As the name suggests, this prenatal test is suitable for the first third of pregnancy, i.e. the first trimester. The test provides the best results between the 12th and 14th week of pregnancy (11+0 to 13+6).
First trimester screening: values conspicuous – what now?
If the first trimester screening shows an increased risk, your doctor will advise you to undergo further tests.
If one of the non-invasive methods gives rise to a suspicion of a chromosomal abnormality or malformation of the child, only invasive methods such as chorionic villus sampling or amniocentesis can ultimately provide more precise information.
First trimester screening: Yes or no?
Whether or not first trimester screening is useful is a matter of much debate among experts. Most women hope that prenatal diagnostics will give them the certainty that their child is healthy. However, this guarantee cannot be given. First trimester screening is not a diagnostic method, but only a statistical assessment of how high the risk of a chromosomal abnormality or malformation is. The result can therefore only serve as a basis for deciding how to proceed. Ultimately, each pregnant woman must decide for herself whether or not to undergo first trimester screening. In any case, complications do not occur.
