Health care providers generally offer screening tests for pregnant women, to check if their baby is at risk of Down Syndrome and other health conditions or disorders. If a baby is diagnosed at an increased risk, or probability, additional tests are offered to make a conclusive diagnosis. At Sirius Health Medical Centre in Chatswood they provide the latest screening tests for pregnant women and below are useful information about the procedures.
Is Testing for Down Syndrome Necessary?
Research says that in Australia, 1 in 1,100 babies is born with Down Syndrome. Down Syndrome is a genetic disorder that affects a certain level of intellectual disability and physical developmental delay. There are 23 chromosomes in each cell of a human body, a baby diagnosed with down syndrome, is born with an extra chromosome 21 present in their cells. Down Syndrome is also known as Trisomy 21. This usually occurs at random during the time of conception. The adverse effects of down syndrome are usually delayed in physical growth, and intellectual disability However, the most recognizable trait is characteristic facial features. Intellectual disability varies widely. The average IQ of a teen or adult person with down syndrome is equal to the mental capacity of an 8- or 9-year-old child.
Will You Be Able to Tell If A Baby Has Down Syndrome in an Ultrasound?
The answer to that question is yes. Ultrasound can detect fluid at the back of a fetus’ neck, which can be an indicator of down syndrome. An ultrasound test measures nuchal translucency. This is an effective method in the early detection of health disorders.
The Two Types of Prenatal Tests for Down Syndrome
Health care professionals can offer down syndrome checks during the early stages of pregnancy, or after the baby is born. Here are the two types of tests:
- Screening Tests: Technically, screening tests do not provide a definitive answer, however, it can tell you if your baby is at a high risk of down syndrome. It is also a harmless method for the mother and baby.
- Diagnostic Tests: The accuracy of this test determines that down syndrome is present. The downside of this test is the possibility of miscarriage. And because of the risk, they are only suggested to women with babies that have an increased risk of down syndrome, based on the result of the screening test.
Pregnant women do not have to undergo these tests if they do not want to. If the baby has an increased risk of the down syndrome from the initial screening test, it is not mandatory to continue with the diagnostic testing. If you think that the risk is not worth it, then you can discuss this with your doctor.
3 Types of Screening for Down Syndrome
The 3 types of screening are the combined first-trimester screening, the non-invasive prenatal testing or NIPT, and the second-trimester screening. The accuracy level varies in each of these steps, and the usual protocol to get a definitive result is a combination of all three tests. However, research shows that the analysis for the second-trimester screening process for down syndrome is more revealing with the help of ultrasound. Before we go into the details, let’s talk about the 3 types of screening first for better understanding.
First Trimester Screening (Combined)
To calculate the chance of detecting several disorders, or abnormalities, this test is done between 9 weeks and 13 weeks, plus another 6 days into the stage of the pregnancy. The method is quite safe for both the mother and the baby. The data is then combined by a computer to produce results.
- Blood test: This method will determine the number of chromosomes that will help detect the risk of down syndrome. Usually taken between 9- and 12-weeks during pregnancy.
- Ultrasound: This is done to measure the thickness of fluid behind the baby’s neck, called nuchal translucency. This is an effective way of down syndrome detection. Usually taken between 12- and 13-weeks during pregnancy.
To detect the chance of down syndrome, the 2 types of tests are combined based on the mother’s age. If the result yields an increased chance of the baby having down syndrome, further testing is offered (optional), to confirm if the baby has down syndrome.
Additional Tests
Non-invasive Prenatal Testing
This test is also called NIPT. This is a newer method that is very sensitive to the screening of down syndrome. The baby’s DNA that passed through the mother’s bloodstream is analyzed via a simple blood test. It has an accuracy of 99% of detecting down syndrome and is taken after 10 weeks into the pregnancy.
Second Trimester Screening
This method is also known as MSS – Maternal Serum Screen, or triple test. Taken between 14 and 18 weeks into the pregnancy. It is usually offered to pregnant women who missed the first-trimester screening. If the result says that there is an increased chance of down syndrome, then diagnostic testing is offered.
Diagnostic Testing
Diagnostic testing is the only way to determine if the baby has down syndrome. The risk of miscarriage is also increased in this procedure, so, it is only offered to women with an increased chance based on the previous tests.
2 Types of Diagnostic Tests
- CVS or Chorionic Villus Sampling: The process involves the taking of cells in the placenta via a needle with the help of ultrasound. This will determine the number of chromosomes in the baby. The procedure is typically taken between 11 and 14 weeks into pregnancy. The chance of miscarriage is less than 1 in 100.
- Amniocentesis: This process is similar to CVS in which a needle is inserted in the abdomen with the help of ultrasound. However, instead of taking cell samples, amniotic fluid is taken instead. The procedure is taken between 15 and 181 weeks into the pregnancy, and also have a chance of miscarriage less than 1 in 100.
Both of these processes are painless and, usually take roughly around 20 minutes.
Nuchal Translucency Significance
The importance of down syndrome early detection is significant for both the baby and the mother’s well-being. Women in general, whatever the age have a slight risk of having a baby with physical, or cognitive disorder. The significance of the nuchal translucency scan will help physicians determine if there is a risk of down syndrome and other kinds of abnormalities.
Conclusion
If the initial result of the screening process says that the baby has an increased risk of down syndrome, it is best to talk to your physician regarding the best possible steps to do afterwards. The risks of diagnostic tests are optional. Pregnant women should always prioritize the safety of the baby. However, understanding the risks and benefits of the procedure is also important. Pregnant women can attend seminars about breastfeeding and how their body will change etc to avoid been overstressed about the fetus health risks.
