Naturally, we do lots of tests before pregnancy. All these tests, of course, related to the maternal health which detect the baby health too, but rare of us seldom know what the test we should do or we are doing in this period. One of the tests we are talking about today is known as CVS – Chorionic Villus Sampling, a test carried out during pregnancy to detect specific abnormalities in an unborn baby.
CVS is a prenatal test that is used to detect birth defects, genetic diseases, and other problems during pregnancy. During the test, a small sample of cells which is called chorionic villi is taken from the placenta where it attaches to the wall of the uterus. Chorionic villi are tiny parts of the placenta that are formed from the fertilized egg, so they have the same genes as the baby.
CVS is offered in pregnancies if you have certain risk factors for having a baby with a birth defect or genetic disease so that problems can be found early in pregnancy. This test can detect your previous pregnancy with foetal problems, such as a baby born with a chromosome abnormality or a mental health condition.
If you have a family history of a condition such as cystic fibrosis or muscular dystrophy, can be detected through this test. An earlier antenatal screening test has suggested that there may be a problem, such as sickle cell anaemia, an inherited blood disorder.
A CVS is usually done between 11 and 13 weeks of pregnancy. In special circumstances, the CVS might be carried out later in your pregnancy. However, it should not be done before 10 weeks of pregnancy. The risk of CVS causing complications, such as miscarriage or birth defects in the baby, is higher if it is carried out before week 10 of the pregnancy. It is also called as chorionic villus biopsy.
CVS is considered 98% accurate in diagnosing chromosomal defects. This procedure also figures out the sex of the baby, which can help rule out or diagnose specific abnormalities associated with that sex. For instance, muscular dystrophy, which is a progressive weakening of muscles, is more common in males. Here’s a look at the circumstances when your doctor may recommend that you go through a CVS test.
• When you or your partner have a family history of disorders like cystic fibrosis or muscular dystrophy
• If you have had spontaneous abortions despite taking good care
• If you will be 35 years or older on your due date, you may be more prone to having a baby with a chromosomal problem like Down syndrome
• If your previous pregnancy was unfortunately marred with foetal abnormalities or when your baby was born with a mental health condition or chromosomal defect
• When an early ultrasound suggests your baby may have structural defects as a result of a chromosomal problem
• When a previous antenatal screening test has indicated the possibility of a problem such as sickle cell anaemia, a genetic blood disorder.
Before performing the CVS test, it is important to provide genetic counselling, which will include an in-depth explanation of the method, risks, and benefits of the procedure.
An ultrasound examination must be done to confirm the stage of pregnancy you are in so that the chorionic villi sample obtained from you is good enough to provide the results.
The process could be a bit painful but it does not take too long to finish. It is possible to extract the sample within minutes. A little cramping and bleeding following the procedure are normal so do not panic at the sight of blood. Make sure you take rest after the procedure for the remaining part of the day and restrict yourself from any physical activity. In case you notice anything unusual such as fluid leakage from the vagina, consult your doctor immediately.