Chorionic Villus Sampling (CVS) is a prenatal test performed between the 10th and 13th weeks of pregnancy to detect genetic abnormalities in the baby. It is particularly useful for diagnosing conditions such as Down syndrome, cystic fibrosis, and other genetic disorders. This test involves taking a small sample of the placenta (chorionic villi) for analysis and is often recommended for women who are at a higher risk of genetic disorders based on age, family history, or abnormal screening results.
In this blog, we will explore how CVS works, who should consider it, the risks involved, and why it is an important diagnostic tool for many parents.
What is Chorionic Villus Sampling (CVS)?
Chorionic Villus Sampling (CVS) is a prenatal test designed to detect certain genetic disorders. During the procedure, a small sample of chorionic villi from the placenta is collected and tested. These cells share the baby’s genetic makeup, allowing doctors to detect chromosomal conditions.
CVS is known for its ability to provide early results, which can be vital for families who want to understand their baby’s health in the first trimester. The test is highly accurate, with results that are almost 99% conclusive for specific conditions.
Who Should Consider CVS?
Not all pregnancies require CVS. It is typically recommended in certain high-risk situations, such as:
- Maternal Age: Women over the age of 35 are at a higher risk for chromosomal abnormalities like Down syndrome.
- Family History: If there is a history of genetic disorders, CVS can help detect if the baby has inherited the condition.
- Abnormal Screening Results: If early blood tests or ultrasounds show signs of potential problems, CVS can confirm or rule out certain conditions.
- Previous Pregnancy with a Genetic Disorder: If a previous child was born with a genetic disorder, CVS may be recommended in future pregnancies to check for similar issues.
How is the CVS Procedure Performed?
CVS can be performed in two ways: transcervical or transabdominal.
- Transcervical CVS: A thin tube is inserted through the cervix to reach the placenta, and a small sample of chorionic villi is removed.
- Transabdominal CVS: A needle is inserted through the abdomen into the uterus to collect the sample.
The choice of method depends on the position of the placenta, determined by an ultrasound before the procedure. The procedure itself takes about 30 minutes, though the actual sampling takes only a few minutes.
What Conditions Can CVS Detect?
CVS is primarily used to detect chromosomal abnormalities such as:
- Down syndrome (Trisomy 21): A condition that causes developmental delays and intellectual disabilities.
- Cystic fibrosis: A genetic disorder affecting the lungs and digestive system.
- Sickle cell anemia: A blood disorder that causes red blood cells to become misshapen.
- Tay-Sachs disease: A fatal genetic disorder that affects nerve cells in the brain and spinal cord.
It is important to note that CVS does not detect all genetic disorders but can identify many severe conditions.
Risks of CVS
CVS is an invasive procedure, and like any medical intervention, it carries some risks. The primary risk is miscarriage, which occurs in about 1 in 100 procedures. Other risks include:
- Infection: Though rare, there is a small risk of infection following the procedure.
- Vaginal bleeding: Some women experience light bleeding afterward, which usually resolves on its own.
- Rh sensitization: If the mother has Rh-negative blood and the baby is Rh-positive, there is a risk of sensitization. However, this can be managed with a Rh immunoglobulin injection.
Why is CVS Important?
CVS provides vital early insights into the baby’s genetic health. For parents facing a higher risk of genetic disorders, this information can be empowering. The test allows families to:
- Make informed decisions about continuing the pregnancy.
- Prepare for medical interventions or specialized care that may be needed after birth.
- Gain peace of mind if the results show no abnormalities.