Taken from http://bebeboom.mk/
In the 12th week of pregnancy, very important ultrasound examination should be done, where your doctor checks the length of the fold of the fetal neck (the length of the nuchal tube), is nasal bone present and among others, the doctor assess the risk of the Down syndrome. After this chek up, it is best from the 13th and 13,5 week of pregnancy to make a Double test – PRISCA 2, which can be done with a blood from a vein of the pregnant woman.
This test is measuring the level of present hormones in the mother’s blood, alpha-fetoprotein AFP, free estriol UEZ and HCG, which indicate a possible risk of chromosomal abnormalities.
If your doctor estimates that it is necessary, after 15 weeks of pregnancy, the mother must do the Triple test – PRISCA 3 test. This test can be made if the pregnant woman haven’t done the previous test, the Double test.
How much the Double and Triple tests are reliable and trustworthy?
The degree of reliability and certainty in the Double test that is usually done from the 15th till the 20th week of pregnancy is 65%, while the reliability and certainty in the Triple test which is done at the same period of time if between 75 – 78%. But, it is worth to mention the fact that the reliability of early Double test PRISCA 1 which needs to be done in 12th week of pregnancy is increased to 80%.
What these tests show?
Based on ultrasound at 12th week of pregnancy and if the Double and Triple test show the overall risk of Down syndrome and other chromosomal abnormalities in the fetus, such as Edwards syndrome and if it transpires that there is a serious chance for chromosome disorders, in particular, if the results of the Triple test are abnormal, your doctor will refer you to do an analysis of amniotic fluid-amniocentesis.
Previously, there was a thinking that during pregnancy the mother’s and a baby’s blood do not mix. But, it is proven that some number of the mother’s cells are present in the fetus’s blood and vice versa, some cells of the fetus (fetal cells) are present in the mother’s blood.
Pregnant women between 11 and 13.6 weeks of pregnancy are doing double hormonal test called PRISCA 1 (in 5 ml venous blood, determines two parameters – free BHCG and PAPP-A.). These values are put into computer program along with the mother’s age, the size of the fetus and the neck’s valuables, so that we can calculate the risk for Down syndrome. And if the reference is bigger than 1:300, we advise karyotyping.
The triple eliminatory test, based on the concentrations of the three parameters – (AFP) (hCG) and free estriol (uE3) levels in pregnant woman, along with the age of the pregnant woman, and the correct data for determined relative pregnancy risk for Down’s syndrome. The test can be performed between 15-20 weeks pregnant, and is among the most reliable tests and it’s most accurate at 16-18 week when UC measured diameter is between 32 and 44 mm.
The values of the chromosomes with a help of a computer program are aligned in a correlation with the age of the pregnant woman, certain ultrasound measurements of the fetus, are you a smoker, diabetic, have got pregnant with some procedure and having on mind all of that, you get a result of certain variability of existence of chromosome disorders.
The triple eliminatory test, besides eliminating the risk of Down’s syndrome, can show a higher risk of possible major irregularities in the development of the neural tube (anenncephalia, myelomeningocella). In those cases, the concentration of AFP is very increased. The test has no valuable use in pregnancies where the woman is receiving insulin.
The fully article can be found on the following link: http://bebeboom.mk/dabl-i-tripl-test-priska-2-i-priska3/