Most pregnant women undergo their first ultrasound at week 12 of their gestation. It is here when it takes advantage to be Triple Screening, a non-invasive test that consists of trying to find, if they exist, chromosomal alterations that could alter the growth of the future baby.
This will help have a better understanding and get closer to what factors can increase risk to suffer certain pathologies. This test is not 100% conclusive but it will bring us closer to measure that risk index that may exist.
What is triple screening?
This test is the so-called triple test. It consists of a blood extraction where an attempt is made to look for evidence that there may be chromosomal alterations such as trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), and neural tube defects.
In many cases, to perform this type of test it is necessary to take into account the age of the mother, the levels of two proteins found in the placenta (PAPP-A and free beta-hCG) and to have evaluated an examination of nuchal translucency.
This type of test, as it has been said, is only communicative but not conclusive. In the event that the proof of some type of conclusive data must be formalized with other types of tests that will be invasive. In this case, a fetal DNA test will have to be done on the maternal blood, or an anmiocentesis or chorionic bipsia.
What women have this test done?
The triple screnning it is usually performed on all pregnant women who may have a low risk of being carriers of a fetus with chromosomal abnormalities.
Women over 35 fall within a high level, those who in a previous pregnancy have had another type of chromosomal abnormality, women with repetitive abortions, who have had a family history related to Down syndrome, who have been in contact with some type of ionizing radiation or those women who have already had offspring of children with congenital malformations.
When is this sample done?
It is done during the first trimester of pregnancy and generally coinciding with the first ultrasound, around the 12th week of gestation.
On other occasions, triple screening is carried out in the beginning of the second trimester of pregnancy around the 15th and 18th week of pregnancy, but never after week 20, since the data that can be provided cannot be very exact.
How is the triple screening test interpreted?
Once the blood test is done, the results will be expected in one or two weeks The test has a diagnostic sensitivity that ranges from a 85% and 90% correct. When your result is higher than 1/250 for trisomy 21,18 or 13 then we are considering that there is a high risk.
It is necessary to collect other types of data such as having found some type of fetal malformation in the ultrasound or collecting data from the history of some chromosomal abnormality in some other pregnancy or in a family history.
After these data, the results will be much better concluded with a chorionic biopsy o amniocentesis.
Other facts about the tripe screenig
The fact of submitting to this type of test is not mandatory. It is important to have knowledge of what is going to be done, since it is a personal decision of the mother who wants to undergo this test. We already know that this type of diagnosis is mainly to conclude that the future baby will not suffer from Down syndrome, since it is usually the most frequent syndrome. It is a question that the future mother has to ask herself, whether to take the test or not, because the decision to continue with the pregnancy or not comes into debate and that falls into an indecision that can raise serious questions about its continuity.