Boston: Down Syndrome - Three "Screening Tests" Are the First Step in Diagnosing Down Syndrome

Boston,

Doctors can make a Down syndrome diagnosis for a baby while the mother is still pregnant. Down syndrome is caused by the presence of an extra 21st chromosome in the baby.

Babies that don’t have Down syndrome have two 21st chromosomes and babies with Down syndrome normally have three 21st chromosomes. People usually have 46 chromosomes – or 26 pairs of chromosomes. Chromosomes are the material in our bodies that gives our bodies instructions as to how to grow, develop and work.

If you’re spending some time reading about Down syndrome you may also see it called Trisomy 21.

Pregnant Mothers Over 35 Are Particularly At Risk

In the past, mothers were given the choice of having tests to determine if their baby might have Down syndrome. Mothers over 35 are particularly at risk to have a Down syndrome baby.

Today most mothers, especially mothers over 35, are strongly encouraged to have the first set of tests, called screening tests, to see if there is any risk of Down syndrome.

Today there are so many things that can be done to help a baby with Down syndrome. Some can be done while the baby is still in the mother’s uterus and some right after birth so it’s good to know as early as possible if your baby has Down syndrome. Some mothers, though, may choose not to have these tests because they don’t want to know, before birth, if their baby has Down syndrome.

Down Syndrome “Screening Tests” are Available During Pregnancy

Three types of screening tests for diagnosing Down Syndrome are common. Screening tests cannot diagnosis Down Syndrome but they can tell your doctor if your baby has some characteristics that might indicate that your baby is at risk for Down Syndrome.

1. Ultrasound – a regular ultrasound or sonogram. Ultrasound allows your doctor to look at a picture of your baby while it’s still in your womb. There are things that a doctor can see in an ultrasound that might make the doctor think that a baby could possibly have Down syndrome. These include:

• A bone in the baby’s legs, called a femur, that’s shorter than usual


• Some heart problems


• Extra skin at the back of the baby’s neck (called “nuchal translucency”)


• Defects in the baby’s stomach or intestines


• Cysts in the part of the baby’s brain where spinal fluid is produced. These cysts are called “choroid plexus cysts.”

2. Maternal Serum Tests – tests of the mother’s blood. These tests work because a mom’s circulation system is shared with her baby. A baby makes chemicals that can be detected in the mother’s blood tests. There are several different kinds of maternal serum, or blood tests, that can be done and some are given in the first trimester (first three months) of pregnancy and some in the second trimester (second three months of pregnancy.)

3. Integrated Screening – is a combination of ultrasound and maternal serum testing. Your doctor will advise you about the best diagnostic testing for Down syndrome given your age, family history and your medical history.

What if the pregnancy tests come back with a possible Down Syndrome diagnosis?

If your doctor is concerned that your baby may have Down syndrome, he or she will probably recommend another series of tests. These tests are called diagnostic tests. To make a definite Down syndrome diagnosis a doctor needs to conduct one of several diagnostic tests that are accurate 98-99% of the time if they come back positive for Down syndrome.

Parents will want to think about whether or not they want to have diagnostic screen testing for their baby and discuss the tests carefully with their doctors. There are pros and cons to diagnostic testing and it’s essential to discuss how important it is to you and to your doctor to know for sure, before the birth of your baby, if your baby will have a Down syndrome diagnosis.

Source by Craig Kendall

Down Syndrome - Three "Screening Tests" Are the First Step in Diagnosing Down Syndrome