Chorionic villus sampling

What is Chorionic Villus Sampling?

Chorionic villus sampling (CVS) is a prenatal test conducted to diagnose chromosomal disorders and certain genetic diseases in a fetus. The procedure involves collecting and testing a sample of cells from the placenta, the organ that serves as the link between the mother and her developing baby.

Preparation for CVS

Women planning to undergo CVS do not need any specific preparation for the procedure. It helps, however, to inform your doctor about the medications (including over-the-counter medications, herbs, and supplements) you are taking, allergies (if any), and any previous surgeries.

Procedure for CVS

Chorionic villus sampling is usually done between the 10th and 12th week of pregnancy. During the procedure, the doctor inserts a thin, flexible tube (catheter) into the vagina, takes it to the womb, and inserts it through the cervix. The doctor then uses ultrasound to guide the catheter to the right area. A tiny sample of cells from the placenta is taken and sent to the laboratory for analysis. The entire process lasts a few minutes and does not cause much pain or discomfort.

Types of CVS

CVS can be divided into two types:

• Transcervical CVS: The tissue sample is taken by inserting a thin tube through the cervix.
• Transthoracic CVS: The tissue sample is taken by inserting a thin needle through the mother’s abdomen.

Why is CVS done?

CVS is done to diagnose chromosomal disorders such as Down syndrome and certain genetic diseases in a fetus, such as cystic fibrosis and Tay-Sachs disease. It is also used to determine the sex of the baby.

When Is CVS done?

CVS is usually done between weeks 10 and 12 of pregnancy, but it can be done as early as 8 weeks after conception. It is important to keep in mind that CVS should not be performed before week 10, as DNA from the placenta and baby are not well developed before that period.

Risks associated with CVS

CVS is generally considered safe, though it may carry certain risks such as miscarriage (1 to 2 percent of cases) and infection. Additionally, there is a slight risk (less than 1 percent) of fetal limb abnormalities due to improper placement of the needle.