Down time filtering

Combined test

What is Down's age?

The most common cause of congenital intellectual disability (1 in 600 births; 1:600) is Down's disease, also known as trisomy 21, when an individual has an extra 21st chromosome in every cell.
In addition to severe mental impairment, this disease can also result in characteristic external signs, which in some cases can already be detected by ultrasound during the fetus's life, while in other cases they are not even evident in the newborn period. The frequency of trisomy 21 increases with maternal age. Over the age of 35, its incidence increases, but expectant mothers often do not know that, in terms of absolute numbers, more children with Down syndrome are born in the 18-35 age group than in those over 35. The explanation for this is that more people get pregnant at a young age. This disease can also affect those who have never had such a disease in their family. Screening is therefore recommended at all maternal ages!

Fetal Down's disease can only be ruled out or recognized with complete certainty by examining the fetus's chromosomes. In order to do this, one of the diagnostic tests (chorion biopsy, also known as placental sampling or amniocentesis, also known as amniotic fluid sampling) must be performed on the mother. However, these tests are not without risk. Sampling can cause a miscarriage in 1% of cases, even if the fetus is completely healthy.

Screening is therefore recommended at all maternal ages!

Fetal Down's disease can only be ruled out or recognized with complete certainty by examining the fetus's chromosomes. In order to do this, one of the diagnostic tests (chorion biopsy, also known as placental sampling or amniocentesis, also known as amniotic fluid sampling) must be performed on the mother. However, these tests are not without risk. Sampling can cause a miscarriage in 1% of cases, even if the fetus is completely healthy. What is Down syndrome screening? Down's disease screening is a complex test, the results of which are evaluated together with the help of a computer program to calculate the probability of the occurrence of Down's disease in each pregnancy. Its purpose is to recognize those cases in which the risk of Down's disease reaches the level above which the diagnostic sampling associated with the risk of miscarriage should be considered, the fetal chromosome test. What is occiput screening? This is an ultrasound examination performed between 11-13 weeks + 6 days of pregnancy, during which the thickness of the fluid collection behind the back of the fetus's neck is measured. A certain amount or thick fluid collection, however, in the case of fetuses with Down's syndrome or with certain types of heart defects or some special syndrome, this amount can be higher in most cases.

According to the FMF regulations, the measurement can only be performed by an authorized, professionally prepared and audited (audited annually) examiner, in the correct position of the fetus, in an ideal plane, at the appropriate magnification, with an ultrasound device of appropriate resolution, with an accuracy of ten millimeters.

Please see the list of examiners audited by the Fetal Medicine Foundation (FMF) in Hungary, who have adequate theoretical and practical experience:

FMF accredited practitionersNT specialists.

Setting all of these up is often extremely time-consuming, so the fetus sometimes has to be guided into the right position with external stimuli, and it may also happen that the examination has to be temporarily interrupted and continued later. VIDEO 2

Additional advantages of occiput screening:

the gestational age can be specified by measuring the sitting height (CRL) [video-3]
in early pregnancy, the normal rate of development of the fetus can be checked
enables the recognition of multiple (twin) pregnancies, or so-called its classification into mono- and dichorial groups
it shows possible developmental disorders that can already be recognized at this age, or it can indicate the presence of disorders that can only be recognized at a later gestational age
It can raise the possibility of other genetic syndromes and heart defects

What is a combined test?

The combined test is a complex test that, based on international and domestic experience, can identify high-risk cases of Down's disease with a hit accuracy of 90%. The test is based on a combination of maternal history data, an ultrasound examination performed according to FMF criteria (occipital fold thickness) and the measurement of two hormones (free B-hCG and PAPP-A) from the mother's blood. The results are analyzed with the help of a computer software developed for this purpose, which can be used to calculate the probability of the occurrence of Down's disease in each pregnancy. The purpose of the test is to identify cases in which the risk of Down's disease reaches a level above which a DNA-based test can be performed from the mother's blood or a diagnostic sampling involving the risk of miscarriage (the invasive fetal chromosome test) is recommended.

FMF AUDITED DOCTORS

The quality of the ultrasound examination is decisive in the effectiveness of the examination. The test can only be accepted if the examining FMF is audited and found at one of the following 5 levels:

1. Doctors with a Diploma in Fetal Medicine - highest level - See the list of those with the highest international ultrasound examination in Hungary: FMF DIPLOMA IN FETAL MEDICINE
2. FMF audited doctors FMF AUDITED DOCTORS
3. FMF audited sonographers
4. Doctors with an FMF license FMF LICENSED DOCTORS
5. FMF licensed sonographers

Based on the fetal occipital fold thickness measured during the ultrasound examination and the results of the biochemical test (free B-hCG or PAPP-A), the computer program indicates that the so-called background risk how it changes. This is how you can calculate the individualized, so-called calculated risk. The results of the tests also enable the risk assessment of Edwards syndrome and Patau syndrome. These are much rarer and more serious chromosomal abnormalities.

The result is a ratio for each of the three disorders (e.g. 1:100, which means that in 1 out of 100 similar cases the fetus actually has Down syndrome, while in 99 cases it does not). The result of the screening test is considered positive if it exceeds a certain threshold value. According to the domestic professional recommendation limit value 1:250. In the case of a higher risk (e.g. 1:100), it may be justified to carry out a fetal free DNA test or one of the diagnostic methods (chorion biopsy or amniocentesis) that can be performed from the mother's blood (in this case, the probability of the occurrence of the disease is almost as high as the chance of miscarriage after taking a fetal sample).

THE negative result of combined test (low risk) does not represent a full guarantee for the health of the fetus, only a indicates a low probability of a chromosomal abnormality after analyzing the aforementioned data.

Some of the filtered cases are so-called it gives a "false positive" result, which means that despite the abnormal values, it is a healthy fetus (which we cannot yet know when the test is performed). This is a small part of all cases, approx. 3-5%-a. We also offer these pregnant women DNA-based tests (fetal free DNA test, invasive sampling).

Further care of the screened positive cases will take place at the Genetic Counselor of the Obstetrics and Gynecology Clinic of DE KK.

What is the Extended Combined Test?

The screening efficiency of the combined test can be further increased if other ultrasound markers are examined during screening. Our doctors routinely check these markers during the examination.

Nasal bone examination [video-4]
Examination of the tricuspid heart valve [image-5]
Ductus venosus hepatic vein flow [video-6]
ARSA - Aberrant subclavian vein examination [video-7]

A negative result of the combined test does not mean a full guarantee of the health of the fetus, it only indicates a low probability of the occurrence of a chromosomal abnormality after analyzing the above-mentioned data.

Some of the filtered cases are so-called it gives a "false positive" result, which means that despite the abnormal values, it is a healthy fetus (which we cannot yet know when the test is performed). This is a small part of all cases, approx. 3-5%-a. We also offer chromosome testing to these pregnant women in order to detect nearly 90% (combined test) of Down syndrome cases.

Screened positive cases can be further treated at the Genetic Counselor of the DE KK Obstetrics and Gynecology Clinic, as this is one of the country's high-quality regional centers providing this kind of care. Of course, filtered cases can be further treated at any private or state-funded institution where they are admitted.

If you have a need to perform the 100% diagnostic test (fetal hair sampling, amniotic fluid sampling) despite the negative combined screening test, you can also do so at the DEKK Obstetrics and Gynecology Clinic's Genetic Counseling.

What is the Free DNA test?

The latest option for fetal Down's disease screening is free DNA tests. The free DNA test is a milestone in the screening of fetal chromosomal disorders, which fulfills the need to screen for certain genetic disorders of the fetus with high safety without endangering the fetus and the mother. It is based on a molecular genetic method capable of examining free fetal DNA segments circulating in the mother's blood, clarifying their origin (i.e. which chromosome they come from) and quantifying them. A fetus with Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), or Patau syndrome (trisomy 13) has an extra amount of free DNA representing chromosome 21, or 18, or 13 releases into the mother's blood, which can be filtered with extremely good efficiency with this new method.

The new method is primarily recommended for pregnant women with a high risk of chromosomal abnormalities:

older maternal age (≥35 years)
confirmed chromosomal abnormality in a previous pregnancy
high risk indicated by traditional screening methods (occiput, combined test) (in these cases, prior consultation with the Genetic Counselor of the DEKK Obstetrics and Gynecology Clinic is required)
At the request of the patient, it can also be performed in low-risk pregnancies, if you want 99.99% safety

The effectiveness of the risk-free test, which can be performed with maternal blood sampling, was determined in international clinical trials on a large patient population. According to clinical studies, a The 99% of Down syndrome fetuses can be detected with the free DNA test. The "false positive" rate is at most 0.2%. If the test gives a positive result (in other words, it indicates Down's disease), then genetic counseling is recommended and sampling of the amniotic fluid or amniotic fluid must be performed.