Chorionic villus sampling is a diagnostic test which is performed during pregnancy in order to identify genetic disorders or other issues. Your doctor may recommend this test if there is a possibility for your baby to be born with certain anomalies or birth defects. This can be done in the first trimester itself, at 10 weeks or more.
Chorionic villus sampling (CVS) involves collecting a sample called chorionic villi from your placenta, close to the uterine wall where it is affixed. Chorionic villi are cells that are formed from the embryo, containing the same genetic information as that of the baby. The evaluation of this sample helps in detecting problems with the the growing fetus.
How effective is CVS?
This test effectively recognizes chromosomal related conditions such as Down syndrome or health issues such as Tay-Sachs or cystic fibrosis. However, CVS will not be able to detect neural tube defects. Other tests may be required, if other conditions are suspected. The early diagnosis of serious conditions with the help of this test, require taking a decision on your part.
Who needs this test?
Your pregnancy may be considered a risk factor if –
- You are above 35 years
- There are cases of genetic disorders in any one of the partner’s family
- The previous screen test results have been abnormal
- You have a child with a rare disease
This test may be performed in any of the two ways depending on the position of your placenta. Transcervical CVS involves taking the tissue sample through cervix. Your doctor will insert a thin tube into your cervix and guide it towards the placenta with the help of ultrasound. Chorionic villi will then be collected carefully into a syringe with the help of the tube. You may feel mild cramps when the cells are being suctioned.
In case of transabdominal CVS, your doctor inserts a long, thin needle into your abdomen. With the help of ultrasound, the needle will be guided into the uterus and towards the placenta. The sample of cells will be collected into the syringe gently. You may feel mild pain and discomfort when it is being extracted.
You should also be aware of the risks associated with this test. Similar to an invasive process, CVS may also cause certain side effects such as –
- Amniotic fluid leak
- Premature delivery
- In rare cases, babies are born with defective limbs, if this test is carried out before 9 weeks gestation.