PREGNANCY SCREENING TESTS
The purpose of screening tests (double, triple, quadruple test); whether the chance of giving birth to a baby with chromosomal anomaly increases or not. For this reason, before starting the applications with the expectant mother, the reliability of the screening tests should be discussed in detail. It should be noted that no screening test will catch all babies with chromosomal abnormalities. Another point is that screening tests will not show any structural anomalies (disability) in the baby. Although screening tests do not have a direct side effect on pregnancy, interventional intervention (amniocentesis, CVS) may have to be performed due to the results and may lead to complications such as loss of pregnancy (result of interventional intervention). may be low). For this reason, since performing unnecessary and many screening tests may cause false results and unnecessary interventions as a result, a single screening test if possible and a detailed (detailed-advanced ultrasound) ultrasound in the following week will be beneficial for catching chromosomal anomalies at the maximum rate.
This test is often 16-18, just like the triple test. It is applied between weeks and weeks, and the power of detecting babies with Down syndrome is 75-80%. Although this rate is a more successful screening test than the triple test, the quadruple test is not preferred because it is performed later than the double combined test and because it has a weaker ability to detect Down syndrome compared to the double combined test. However, 11-14. If you missed the double combined test between weeks and weeks, it would be appropriate to have a quad test instead of the triple test as a screening test for chromosomal anomalies.
What Are the Advantages and Disadvantages of the NIPT Test?
Although it allows to detect serious chromosomal anomalies encountered during pregnancy and can reach delivery at a very early stage, it has a much higher reliability rate than double and triple screening tests performed in routine pregnancy follow-ups. Since no interventional intervention is required, there is no possibility of complications and miscarriage due to the procedure.
A low risk NIPT test does not mean that the baby will be completely genetically healthy, as the test only examines certain DNA regions. Although it has an accuracy rate of over 98% in terms of the chromosomes examined and genetic diseases, the NIPT test is a screening test, not a diagnostic test. Therefore, if the result is risky, it must be supported by an interventional prenatal test.
When And How Is The NIPT Test Done?
In order for the test to be applicable, a certain amount of fetal DNA obtained from maternal blood must be present. For this reason, it is recommended to be done from the 10th week of pregnancy. There is a high risk of not getting results in previous tests. Taking 10 cc of blood into special tubes produced for the test is sufficient for the study. However, in some special cases (if sufficient fetal DNA cannot be obtained, the test may be repeated or canceled.
First Trimester Screening Test - Double Combined Test (double Test):
While the baby in the mother's womb is lying in the side position, the transparent area behind the nape can be seen between the 11th and 14th days of pregnancy. By measuring HCG + PAPP-A from the blood sample taken from the mother (with the addition of age and gestational week parameters), a double combined test is performed. This screening test is currently the most successful test in detecting babies with chromosomal anomalies (eg, Down syndrome) and is recommended for all expectant mothers regardless of age. With the double combined test, approximately 100 out of 90 babies born with Down syndrome can be detected. If your Down syndrome risk is more than 1/270 or only NT (nape thickness measurement) is more than 3mm as a result of the double combined test, CVS (chorionic villus sampling) is performed within the current week (between 11-14 weeks) (with FISH method in one day if necessary). ) you can learn 100% of your baby's chromosome structure. If you have had this test and you are going to have a detailed ultrasound (detailed-advanced ultrasound) in the later stages of pregnancy, you do not need to have another biochemical screening test.Triple Test:
The triple test is usually done between 16-18 weeks of pregnancy. done between weeks. This test; It gives information about the risk of your baby having Down syndrome and Trisomy 3 by looking at HCG, E18 and AFP from the blood taken from the mother and combining these values with the mother's age and the baby's week. This test is a screening test and it is impossible for the triple test to predict all possible babies with Down syndrome. Today, this test has lost its effectiveness due to its weak power to detect a baby with Down syndrome. If amniocentesis is applied to risky mothers as a result of this test, only 100-60 babies out of 65 who can be born with Down syndrome (Mongolian baby) can be caught.Quad Test:
Quadruple test is the calculation obtained by measuring HCG + AFP + E3 + Inhibin-A levels from the blood taken from the expectant mother and combining these values with parameters such as gestational week and maternal age.This test is often 16-18, just like the triple test. It is applied between weeks and weeks, and the power of detecting babies with Down syndrome is 75-80%. Although this rate is a more successful screening test than the triple test, the quadruple test is not preferred because it is performed later than the double combined test and because it has a weaker ability to detect Down syndrome compared to the double combined test. However, 11-14. If you missed the double combined test between weeks and weeks, it would be appropriate to have a quad test instead of the triple test as a screening test for chromosomal anomalies.
NIPT test:
It is the screening of genetic diseases in the fetus on the blood sample taken only from the mother without any interventional intervention. From the first weeks of pregnancy, some fetal cells enter the mother's bloodstream and are present in the mother's blood during pregnancy. With this test, some microdeletion syndromes can be detected along with the most common chromosomal abnormalities (Down syndrome, Patau syndrome, Edwards syndrome) during pregnancy.What Are the Advantages and Disadvantages of the NIPT Test?
Although it allows to detect serious chromosomal anomalies encountered during pregnancy and can reach delivery at a very early stage, it has a much higher reliability rate than double and triple screening tests performed in routine pregnancy follow-ups. Since no interventional intervention is required, there is no possibility of complications and miscarriage due to the procedure.
A low risk NIPT test does not mean that the baby will be completely genetically healthy, as the test only examines certain DNA regions. Although it has an accuracy rate of over 98% in terms of the chromosomes examined and genetic diseases, the NIPT test is a screening test, not a diagnostic test. Therefore, if the result is risky, it must be supported by an interventional prenatal test.
When And How Is The NIPT Test Done?
In order for the test to be applicable, a certain amount of fetal DNA obtained from maternal blood must be present. For this reason, it is recommended to be done from the 10th week of pregnancy. There is a high risk of not getting results in previous tests. Taking 10 cc of blood into special tubes produced for the test is sufficient for the study. However, in some special cases (if sufficient fetal DNA cannot be obtained, the test may be repeated or canceled.
