01 Feb Pregnant? Learn more about Chorionic Villus Sampling (CVS)
Chorionic Villus Sampling (CVS) is a prenatal test done around the 10th to 13th week to check for certain genetic problems as well as chromosomal abnormalities1. In this test, sample tissue is taken from the small finger-like protrusions on the placenta and sent to a lab for examination. A finger-like protrusion is called the chorionic villi, hence the name of the test1. The placenta is an organ that is formed during pregnancy and it is responsible for carrying blood, oxygen, and nutrients to the fetus. It is also responsible for carrying waste from the fetus, as such the placenta contains a significant amount of the fetus’s cells at any point during pregnancy. As this is one of the earliest tests used to diagnose birth defects such as Down syndrome, Turner syndrome, etc., mothers with a higher risk of having babies with some of these birth defects are advised to take this test. This is because, unlike its counterpart amniocentesis, it is done a lot earlier allowing for the mother to decide whether to carry the fetus to term with lower risks to the mother if termination is the option chosen. In some cases, certain conditions may be treatable if caught early. As such, if you have a family history of chromosomal or genetic issues, contact your doctor or visit us at 67th Street OB/GYN- Total Women’s Health care and speak with one of our OB/GYNs in Manhattan today.
In what case is this test recommended?
Although most genetic issues cannot be treated, some mothers would rather know early then wait regardless of their decision to keep the fetus. Below are some reasons your doctor may recommend you take this test:
- Family history: There is a higher risk if either you or your partner’s family has a history of genetic health problems. These conditions can be passed down from the mother and father regardless of if they have those health issues themselves. There is a chance that they still carry the genes responsible2.
- Mother’s age: women over the age of 35 have a higher risk of having babies with certain birth defects.
- Positive results from other prenatal screening: If you receive another abnormal result from a prenatal screening test, your doctor may advise you to get a CVS test to rule out chromosomal/genetic issues3.
- Previous chromosomal/genetic issues with previous pregnancies: If you have had a previous pregnancy or a child with birth defects, then there is a higher risk of birth defect with your current pregnancy. As such your doctor will recommend this test to ascertain the genetic/chromosomal health of your current pregnancy.
What are the risks associated with CVS?
A CVS test increases the risk of miscarriage to about 1 in every 1004. However, the risk is mitigated when a doctor experienced in this procedure performs it Below is a list of other health risks associated with this procedure:
- Preterm labor
- Defects in the limbs of infants; this is greatly reduced if the procedure is done after the 10th week. As such, most doctors will not perform this procedure before.
- Leaking of the amniotic fluid
Patients are advised to inform their doctors immediately if they notice vaginal bleeding, amniotic discharge, fevers, etc., as this may be a sign of a serious infection or complication.
How is this test done?
Before the test, your health provider will perform an ultrasound to check the position of the placenta. This image will then be used as a guide during the procedure. There are two ways CVS can be performed; transabdominal or transcervical. In the transabdominal CVS, the abdomen is cleaned with antiseptic, and a long, thin needle is inserted through the abdominal wall and into the uterus3. The tissue sample is then collected in a syringe. While in transcervical CVS, the vagina and cervix are cleaned with antiseptic. Here a thin, hollow tube is passed through your cervical opening and gentle suction is used to retrieve tissue samples from the placenta.
It usually takes about 7 days for the results to come back. Although it is often chosen over amniocentesis for those who are interested in early detection, it does not test for neural tube issues. Hence an amniocentesis will still be needed if you have a family history of spina bifida.
At 67th Street OB/GYN-Total Women’s Health Care, we provide specialists and counselors to assist mothers before and after every test as to assure both the mental and physical health of both mother and child. Consult with one of our experienced obstetrician in Manhattan for more information.