If you are a mother-to-be, you probably worry a lot about the little one in your womb, right? It is normal to wonder if he is healthy and if he has any problems. At such times, a special test called ``Chorionic Villus Sampling`` or ``CVS`` test is available that helps to detect some genetic conditions or congenital disorders in the baby. Shall we talk about this in more detail?
Simply put, this `CVS` test is a test that can be done very early in pregnancy, between 10 and 13 weeks. It involves taking a very small sample of cells from the placenta, called `Chorionic villi`, and examining them. Since these `Chorionic villi` cells are produced by the fertilized egg, their genetic information is usually the same as the baby's genetic information. So, these cells are sent to a laboratory and analyzed to see if the baby has any genetic conditions. This can even determine the baby's gender.
Why is this CVS test done? Who is it recommended for?
Now you may be wondering, does everyone need to have this `CVS` test? Not really. It is not a mandatory part of your prenatal care. Doctors only recommend this test for people with certain risk factors, or if other non-invasive prenatal screening or ultrasound scans show any abnormalities. However, the decision to have this test or not is up to you . You can discuss the pros and cons of this with your doctor and make your decision.
Doctors may suggest a CVS test in the following cases:
- If you have a previous child with a genetic condition.
- If you are 35 years old or older when you have a baby.
- If a previous scan or other test has shown that the baby is at increased risk of having a genetic condition.
- If you, your partner, or anyone in your family has a genetic disorder (or has a history of such a condition).
When is it okay to skip the CVS test?
However, in some cases, doctors may advise you not to have this test. Let's see when those are.
- If you have had vaginal bleeding during your pregnancy.
- If you have an infection, for example a sexually transmitted infection (STI).
What conditions can be detected by CVS?
What exactly can be detected with this `CVS` test? This mainly helps to identify some genetic diseases, especially problems with chromosomes. Do you know that chromosomes are the things that contain the `DNA` and genetic makeup of the baby. So, this test can check whether there are too many of these chromosomes, too few, or if there are major changes in the structure of the chromosomes. It is because of such chromosomal changes that some congenital disorders and other health problems occur.
To give a few examples:
- Down syndrome or Trisomy 21
- Cystic fibrosis
- Sickle cell disease
- Tay-Sachs disease
- Trisomy 18 or Edward syndrome
- Trisomy 13 or Patau Syndrome
Are there things that a CVS test can't detect?
Yes, one thing to remember. This `CVS` test cannot detect all birth defects . For example, things like `Neural tube defects (NTDs)`, which are problems in the baby's spine or brain, cannot be detected by this test. Have you heard of `(Spina bifida)`? Those are the things. There are other tests to detect such conditions, for example, `(Alpha-fetoprotein (AFP) test)` is good, and `(Amniocentesis)` is good.
Also, some structural defects in the baby's body, such as heart conditions, cleft lip, or cleft palate, cannot be detected by this `CVS` test. These can usually be detected by an `Ultrasound` scan, which is usually done between 18 and 20 weeks of pregnancy.
What happens before the CVS test?
Okay, let's say you've decided to have a CVS test. What happens before that? You'll usually be referred for genetic counseling with a genetic counselor or a maternal-fetal medicine specialist. This counselor will explain the risks and benefits of the test to you. In addition, an ultrasound scan will be done to see exactly how many weeks pregnant you are. This will help determine the best time to have a CVS test.
How is the CVS test done? Does it hurt?
A question that many people have is whether the CVS test hurts. It's not really painful, but you may feel a little discomfort. There are two ways doctors do this test:
1. Through the vagina (Trans-cervical method)
What happens in this is, a device called a `(Speculum)` is inserted into your vagina. It is a thin device shaped like a duck's beak, you may have seen this if you have had a `(Pap test)`. This is used to widen the walls of the vagina a little, and the doctor inserts a thin plastic tube through the `(Cervix)`. Then, under the guidance of an `(Ultrasound)` scan, the tube is sent to the place where the `(Placenta)` is, and from there, the `(Chorionic villi)` cell sample is taken.
2. Through the abdomen (Trans-abdominal method)
In this procedure, guided by an ultrasound scan, the doctor inserts a thin needle through the skin of your abdomen into the placenta and takes a sample of cells. In this transabdominal procedure, you may be given local anesthesia to reduce discomfort.
Both of these methods take less than 30 minutes to complete the test.
What happens after the CVS test?
You can go home immediately after the CVS test. It's best to rest for a few hours after you go home. Most people can resume normal activities the next day. However, your doctor may ask you to avoid sexual activity, exercise, or strenuous activities for two to three days .
Do I need to have a CVS test a second time?
Sometimes, a second CVS test may be needed. This is very rare. This means that if the first test doesn't collect enough cells, you may need to do it a second time to get the required number of cells.
Also, if you are having twins, and each baby has separate placentas, then you may need to have two CVS tests for each baby.
What are the risks and side effects of the CVS test?
After the test, you may feel a slight cramp in your stomach. Vaginal spotting is also normal. If the test was done through the abdomen, you may feel a slight cramping pain in your stomach.
The CVS test is generally safe, but it is not without some risks . It is important to discuss these risks with your doctor and understand them. Let's take a look at what those risks are:
- Miscarriage: The risk of miscarriage from a CVS test is less than 1 in 100, or less than 1% . That's a very low percentage.
- Infection: As with any medical procedure, there is a very small chance of infection.
- Limb deformities: Very rarely, especially if the CVS test is done before 10 weeks of pregnancy, there is a chance that the baby will be born with a limb deformity. That is why it is important to do this on time.
- Bleeding: While some bleeding is normal, in rare cases, there may be heavy vaginal bleeding after CVS.
- Leaking amniotic fluid: Sometimes, the amniotic fluid (the fluid surrounding the baby) can leak too much. This can cause complications during pregnancy.
- Rh sensitization: This happens when your blood type is Rh-negative and your unborn baby is Rh-positive, and the two blood types mix. However, there is treatment for this.
What are the benefits of CVS testing?
The biggest advantage of this `CVS` test is that you can know the results of genetic tests early in the pregnancy . Knowing this information in advance allows you to make health decisions faster.
For example, you can prepare in advance for any special care your baby may need after birth. Or, this information can be important when deciding whether to continue the pregnancy or not.
Another important advantage is that this `CVS` test is about 99% accurate . This means that you can trust the results of this test.
How long does it take to get the results of the CVS test?
The doctor takes a sample of the `(Chorionic villi)` and sends it to a laboratory. The specialists there grow the cells in a special liquid and test them over a few days. You can usually get the initial results within a few days. However, some conditions take a little longer to test. It can take up to 10 days or two weeks for these results to come back. Your genetic counselor will contact you with the final results and talk to you about them. If necessary, they can also discuss further tests that you need to do.
How accurate is the CVS test?
As I mentioned before, the CVS test is about 99% accurate . However, this test cannot accurately determine the severity of the genetic condition.
Also, sometimes the test results can be placental-specific. That is, the abnormality is only in the placenta and does not affect the baby in the womb. This only happens in 1% to 2% of all cases.
What to do if the CVS test results are positive?
If the results of the CVS test show that your unborn baby has a genetic condition, you can talk to your counselor, your partner, and your doctor to decide what to do next. Your doctor or genetic counselor can help you understand what the CVS test results really mean. Then you can make the best decisions about moving forward.
When should I see a doctor after a CVS test?
If you experience any abdominal pain, cramping, or bleeding that does not go away or increases after a CVS, see your doctor immediately. You should also tell your doctor if you have any of the following symptoms:
- If you feel like amniotic fluid is leaking (it may feel like you are passing a little urine).
- If you feel like you're getting a cold and fever.
- If you have contractions along with stomach pain.
- If you have a fever.
What is the difference between a CVS test and an Amniocentesis test?
Another question that many people ask is what is the difference between the `CVS` test and the `(Amniocentesis)` test. Both of these are tests that look at the genetic conditions of the baby in the womb. However, there are several differences between the two:
- When: These two tests are done at different times during pregnancy. CVS is done early in pregnancy (between 10 and 12 weeks), so you can find out sooner if your baby has a genetic condition. Amniocentesis is done around 16 weeks of pregnancy.
- Conditions that can be detected: Amniocentesis can detect conditions such as neural tube defects (NTDs) and spina bifida. CVS cannot detect these conditions.
- Risk of miscarriage: The risk of miscarriage during the ``Amniocentesis'' test is slightly lower than ``CVS''.
- Rh incompatibility: Rh incompatibility can be tested for through amniocentesis.
- Confirmation: Very rarely, an amniocentesis test may be performed to confirm the results of a CVS test.
Your doctor can discuss your risk factors and recommend that you have one, both, or neither of these tests.
What questions should I ask the doctor about the CVS test?
If you are pregnant, it is very important to ask your doctor questions like these:
- "Do I need to have prenatal testing during pregnancy?"
- "Is my baby at increased risk of having a chromosomal problem or other genetic problem?"
- "Is the `CVS` test or the `(Amniocentesis)` test better for me?"
- "What is the risk of miscarriage if I do this test?"
- "What issues should I be aware of after the `CVS` test?"
- "What exactly can I learn from the results of the `CVS` test?"
The most important things for you to remember
Chorionic Villus Sampling (CVS) is a test that checks for certain genetic problems in your baby. It is not a mandatory test . If you decide to have it, it is usually done between 10 and 13 weeks of pregnancy. The test is safe and the results are accurate, but there are some risks. The results of the CVS test can help you make important health decisions. If you are at high risk of having a baby with a genetic condition, talk to your doctor. They will help you decide if the CVS test is right for you.
` CVS test, pregnancy tests, genetic diseases, placenta, birth defects, (Chorionic Villus Sampling), (Prenatal Diagnosis)
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