Sequential Screening – Everything You Need To Know

Sequential Screening

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You are just getting used the do’s and dont’s of pregnancy but do you also worry about your baby? Could there be any birth defects, a abnormalities or any genetic issues with my baby? Is there a certain way by which you may derive some kind of assurance?

If you have such questions and want to know if there is a way to know about your baby’s health and progress, you are at the right place. We have an answer to all your questions queries.Sequential screening during pregnancy is a way of finding out whether your baby has any abnormalities.Read on to know more.

What Is Sequential Screening?

Sequential screenings are two-stage tests which you can avail in the first and second trimester to know whether he/she has the Down syndrome, Trisomy 18, or Open Spina Bifida. Most of the parents decide to undergo this test ,to check if the baby is having any chromosomal irregularity or the Down syndrome. It’s just a screening test and doesn’t confirm if there is an abnormality. It’s more of an assessment and provides you with the result saying whether the baby could have chances of such issues. For a confirmation, a diagnostic test is suggested like amniocentesis which confirms if the baby is suffering from such a condition [1]

How Would The Test Be Performed?

Stage 1:

Sequential screening test is done in two stages.The first stage test is conducted anywhere ten to thirteen weeks of pregnancy .The Modus Operandi for this test is very simple. You would need to take an appointment at the scanning/diagnostic centre. Once you reach the centre, the doctor would do an ultrasound and take your blood samples.

Your blood sample is sent for a test to determine the measurement of two proteins – pregnancy-associated plasma protein A (PAPP-A) and human chorionic gonadotropin (hCG). The ultrasound examination is done to measure the nuchal translucency (NT). Nuchal translucency, in a layman’s terms is a group of fluids in the back of the baby’s neck. Studies have shown that the fetus with Trisomy 18 and the Down Syndrome is likely to have bigger NT measurements than those of babies lacking in these conditions [1][2].

There is no fasting or other preparation needed before having the sequential integrated screening test done.

Stage 2:

The second stage test is conducted anywhere from from 15 to 21 weeks of pregnancy. The Modus Operandi for this test is very simple. You would need to take an appointment with the scanning/diagnostic centre. Once you reach the centre, the doctor would take your blood samples.

Your blood sample is sent for a test to measure the content of these 4 substances – Alpha-fetoprotein (AFP), HCG, Unconjugated Estriol (uE3) and Dimeric Inhibin A (DIA). [2]

How Long Would I have To Wait For The Result?

The sequential screening results takes less than a week once your sample has been taken. [3]

What Does The Result Mean To Me?

The result reflects the fact that how much your baby is numerically at a risk to chromosomal irregularities. The risk calculations made are matched up to the already established cutoff. If the risk is greater than the cutoff, its considered to be a positive test, and a woman may be at a risk of having some chromosomal irregularities. And if The it’s lower than the cutoff its obviously negative.The two stage results, along with your weight and age are pooled in to get the result of the possibility of the Down Syndrome. In stage 2 you had have the measurement of AFP, which helps them to find the odds of getting the open Spina Bifida. And other markers determine the Trisomy 18 condition.

What’s The Accuracy Of This Screening Test?

As per the risk assessment, it is considered to be providing accurate results. However, studies have shown that 90% of women are screenED positive for the Down Syndrome and 80 % are screened positive for Open Spina Bifida. That means 9 out of 10 are shown as positive for the Down Syndrome and 8 out of 10 are shown as positive for Open Spina Bifida. P Pregnant mothers could suffer from these conditions. To bring to your notice again, this test is for screening only, and a diagnosis is a better way to get the accurate results. [1][ [4]

What Is The Down Syndrome, Spina Bifida And Trisomy 18?

The Down syndrome also called as Trisomy 21 is a genetic condition caused by the existence of an additional copy of chromosome 21. Children with the Down Syndrome usually experience delays in growth and to some degree, mental retardation is also seen. They are at risk of having ailments like heart defects, thyroid, respiratory issues, weak sights and hearing difficulties. [4]

Trisomy 18, or the Edward Syndrome is again a chromosomal abnormality usually caused by the presence of all or an element of an added chromosome 18.If any children have this condition, it causes severe mental retardation, and there could be multiple birth defects in the child [6][4]

Spina Bifida, which means the Split spine in Latin, is a congenital abnormality and the main cause of the condition is deficient closing of the embryonic neural tube. Physically, one can attempt to see if the newborn has symptoms of Spina Bifida. On the infant’s skin, the Spina Bifida blemishes appear like a fat collection or a simple dimple or a birthmark. [5][8]

What Are The Other Diagnostic Tools I can Consider If I’m Screened Positive:

Chorionic villus sampling and amniocentesis are the two diagnostics tools which you can avail to confirm the results, whether your baby is developing any of the above conditions. The accuracy of these procedures is 99.9 % correct. [4][9]

It’s better to consult your gynecologist before going for these tests, as studies have shown that there are very slight chances of miscarriages due to these procedures. [4]

Would The Test Also Work Accurately For Twins:

Studies have shown that for twins the assessment is a bit tricky, and accuracy is a bit lower than compared to a single fetus. Depending upon the approach some may provide a single report, and few may give you two reports. [4]

How was your experience with screening? Do let us know in comments section.

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