Fetal
Method
Tiny fragments of DNA (genetic material) circulate in the blood plasma of every human being. Pregnant women also have fragments of genetic material from the placenta in their blood (up to ten per cent). Since 2013, it has been possible to analyse the genetic material fragments from the placenta by taking a simple blood sample from the mother and thus obtain a precise statistical statement on a selection of chromosomal disorders.
This method is called a "DNA blood test", "prenatal test" or "NIPT (non-invasive prenatal test)".
This method can be used, for example, to rule out foetal trisomy 21 with even greater certainty than is possible with ultrasound. Apart from providing information about trisomies (and in the case of the fetalis® test also about monosomy X), the test does not provide any information about the health of your child. For this reason, we only ever offer the DNA blood test in combination with an early organ examination. Further information is also available at INFORMATION ON PRENATAL GENETICS.
Due to the current situation, an article about the: INTRODUCTION OF NIPT AS A HEALTH INSURANCE BENEFIT
Early organ examination
A DNA blood test is always carried out in combination with an early organ examination. This is important as a whole range of developmental disorders (e.g. malformations) can already be ruled out in the first trimester. In the case of abnormal findings, we may even decide not to carry out a blood test and a diagnostic puncture may be necessary.
Questions or appointments?
Do you have further questions on the subject of "DNA testing" or would you like to make an appointment at our practice for prenatal medicine and genetics?
Which foetal DNA tests do we offer?
We offer pregnant women two foetal DNA tests that can be used if you only want to find out the probability of one of these trisomies or monosomy X in your unborn child and do not want an amniocentesis or placental biopsy.
PraenaTest
The COMPANY LIFECODEXX has been offering the so-called PraenaTest since 2012. This makes it possible to test for trisomies 13, 18 and 21 using maternal blood.
fetalis® test
The COMPANY AMEDES offers the fetalis® test, which also provides information on trisomies 13, 18 and 21 and (in contrast to the other two tests) on monosomy X using maternal blood.
Limitations of foetal DNA tests
Using foetal DNA tests, your unborn child can only be tested for trisomy 21 (Down syndrome), trisomy 18 (Edwards' syndrome), trisomy 13 (Pätau syndrome) and, in the case of the fetalis® test, additionally for monosomy X. As a result, only 3-4 of a large number of genetic disorders can be tested and cannot be recognised or ruled out with absolute certainty. Trisomy 21 and trisomy 18 are correctly diagnosed in around 99 per cent of cases using the fetal DNA tests. This means that one in 100 unborn babies affected by one of these trisomies is not recognised. The detection rate for trisomy 13 appears to be worse.
The foetal DNA tests are unsuccessful in two to three per cent of cases, in which case the analysis of the mother's blood provides no information. According to previous studies, out of 300 trisomy diagnoses using foetal DNA tests, one proved to be erroneous. Accordingly, an abnormal blood test must be followed by an amniocentesis or chorionic villus sampling to verify the findings. foetal DNA tests should not currently be carried out in twin pregnancies. This also applies to pregnancies in which two embryos were originally created but only one has developed.
General information on foetal DNA tests
Foetal DNA tests are possible as early as the ninth week of pregnancy. Pregnant women who are interested in foetal DNA tests are offered individual genetic counselling and a Ultrasound examination between 11+0 and 13+0 weeks of pregnancy. Of course, the test can also be carried out later.
If after the genetic counselling If you wish to have a foetal DNA test as early as possible, we will carry out the necessary examination.
When making your decision, please bear in mind that an ultrasound scan after the eleventh week is much more informative than at an earlier stage. Most pregnant women decide whether a placental biopsy, a foetal DNA test or even the omission of these examinations makes sense based on the ultrasound examination together with the examiner.
At this point, the phase of early miscarriages is largely complete. In addition, the proportion of foetal DNA in the mother's blood is usually higher in this period than in the early weeks of pregnancy. Accordingly, test failures are very rare.
Thanks to the Ultrasound examination Between the early 12th and 14th week of pregnancy, we can tell most pregnant women or parents-to-be early on that their child is developing well and on time. Many risks for the further course of the pregnancy (restricted placental function, risk of premature birth, high blood pressure in the mother) can already be recognised at this stage.
If abnormalities are found on the ultrasound image, there may be a variety of genetic or non-genetic reasons for this. To the Clarification of these abnormalities of the unborn child, a foetal DNA test is not suitable.
PraenaTest
The PraenaTest is carried out by the LifeCodexx laboratory in Constance. As a self-payer/privately insured person, the costs are as follows 169,- € for the examination for all three trisomies (Trisomy 13,18, 21) .
Determining the gender costs additional 17,50,- €
Additional options (e.g. microdeletion syndromes) possible after detailed consultation.
fetalis® test
The costs for the fetalis® test for self-payers/privately insured persons are as follows 204,- € and include the test kit and its analysis. The following are tested: Trisomy 13, 18, 21 - carried out in the Amedes laboratory (Germany).
Determining the gender costs additional 17,50,- €
The respective cost billing is always carried out directly by the provider.
Only the doctors who supervise and send in the test are responsible for explaining the significance, safety and limitations of the respective test.
There are other tests that can be carried out during pregnancy (e.g. first trimester screening). These tests can also determine whether there is a high probability that your baby could have a chromosomal disorder, such as Down's syndrome. However, the probability of false results is higher with older types of these screening tests.
This means that a chromosomal disorder may go undetected in some pregnancies or that women with healthy babies may mistakenly receive a result that indicates a higher probability of a chromosomal disorder.
In order to determine with absolute certainty whether the baby actually has a chromosomal disorder, examinations of the placenta (the placenta) or the amniotic fluid, such as a CHORIONIC VILLUS SAMPLING or a AMNIOCENTESEcan be carried out. Both tests carry risks, such as a small risk of miscarriage. Talk to your doctor or counsellor if you have any further questions about your examination options. In any case, these invasive examinations are recommended for manifest abnormalities.
It is important that you are informed in detail about the possibilities and limitations of this test method. We take the time to answer your questions and clarify whether a blood test is right for you.
An early malformation ultrasound is then carried out. We will show you your child from head to toe and explain which organs can already be assessed.
The blood sample is then taken - the result usually takes 3-5 days and will be communicated to you by telephone. If there is an abnormal test result, a diagnostic puncture (a CHORIONIC VILLUS BIOPSY or a AMNIOCENTESIS).
The PraenaTest cannot be carried out if there was originally a twin system. The fetalis® test is also available for twin pregnancies. but not suitable for triplet pregnancies or in the case of a vanishing twin.
Not all test providers are suitable for artificial insemination or egg donation.
If an abnormality is present (e.g. a recognisable heart defect or a very clear nuchal translucency widening of 3.5 mm or more), it is also not advisable to carry out a DNA blood test.
