Genetic testing during pregnancy: Let's know everything about the Karyotype Test!

When you are pregnant, the doctor asks you to do various tests, right? Sometimes when you hear the names of these medical tests, you feel a little scared and curious. For many people, a test that is a little unfamiliar, but very important, is called a karyotype test. Some people also call it a genetic test, a chromosome test, or a cytogenetic analysis. Don't worry, these names refer to the same test. Today, we will talk about this very simply, in a way that you can understand.

What exactly is this Karyotype Test?

Simply put, a karyotype test takes a very close look at the chromosomes inside our body's cells. Think of these chromosomes as the blueprint for how our body will be built. This test looks for any changes or abnormalities in this blueprint.

During your pregnancy, your doctor will likely order screening tests to check for certain genetic and chromosomal conditions during the first trimester and the second trimester. Most of the time, the results of these tests are within the normal range. No further testing is needed.

However, if those initial tests somehow suggest that there may be a problem, your doctor may suggest you do another test, such as a Karyotype test. This can confirm with certainty whether or not the baby growing in the womb actually has a genetic or chromosomal problem.

What does a karyotype test look for?

Normally, a healthy person has 46 chromosomes. A baby receives 23 of these from the mother and the other 23 from the father.

Sometimes, a baby can have an extra chromosome, one chromosome is missing, or there may be an abnormal change in one of the chromosomes. A karyotype test can tell exactly if this is the case. These are some of the conditions that doctors mainly look for with this test.

• If you are having difficulty conceiving a child , or have had several miscarriages , your doctor may perform this test to check for any problems with your or your partner's chromosomes.
• Find out if you can pass on a genetic condition to your child.
• If a stillbirth occurs, confirm whether the cause is a genetic problem.
• Find the cause of any physical or developmental problems your baby or toddler may be having.
• In the rare case where the sex of a newborn is unclear, confirm it.
• Some types of cancer can cause changes in chromosomes. A karyotype test can help determine the right treatment.

What are these types of Karyotype tests and when are they done?

These tests can only be done at certain weeks of pregnancy. Your doctor will decide which test is best for you, depending on how far along you are in your pregnancy and your risk factors.

The baby is slightly more likely to have a chromosomal problem in the following cases:

• If you are over 35 years old.
• If you already have a child with a chromosomal disorder, or if someone in your family has the condition.
• If you or your partner have any abnormalities in their chromosomes.
• If you have had previous miscarriages or stillbirths.

There are two main types of tests performed:

1. Chorionic Villus Sampling (CVS)

In this, the doctor uses a long needle to remove a very small sample of tissue from the placenta , which provides nourishment to the baby. These cells are sent to a lab for testing. This can help determine if the baby has genetic problems such as Down syndrome, trisomy 13, or trisomy 18.

• When to do it: Between 10 and 13 weeks of pregnancy.
• Risks: There is a very small risk of miscarriage from this test (about 1 in 100 women who have the test). There is also some risk to the baby, so doctors only recommend it if there is a high risk of the baby having a problem.

2. Amniocentesis

In this test, the doctor inserts a long needle through your abdomen and takes a small amount of the amniotic fluid that surrounds the baby in the womb. The baby's cells in this fluid are sent for testing. As well as all the genetic problems that the CVS test looks for, it can also detect serious conditions that affect the baby's brain or spinal cord (neural tube defects).

• When to do it: Between 15 and 20 weeks of pregnancy.
• Risk: There is still a small risk of miscarriage, but it is lower than with CVS (about 1 in 200 women tested).

Are there any risks in these tests?

Yes, as we discussed earlier, there are some risks associated with the methods used to obtain these cells. CVS or Amniocentesis can very rarely cause miscarriage . There is also a small chance of heavy bleeding or infection. Your doctor will discuss all of this with you in detail. So before you panic, ask your doctor any questions you may have.

What happens after the test results come in?

This is the most important thing. The results of a karyotype test are very specific . That is, once the results are received, you can know for sure whether the baby 'has' a genetic problem or 'doesn't'.

This is not like the previous screening tests. They only said whether the risk was 'high' or 'low'. But the result of the Karyotype test is not a guess, but a confirmation.

Once you receive the results, your doctor will discuss them with you in detail and explain what steps you need to take next.

Karyotype test, genetic testing, chromosomes, pregnancy, Down syndrome, Amniocentesis, CVS, baby's health, genetic diseases