Chorionic Villus Sampling (CVS)

CVS is a procedure in which a small amount of tissue (chorionic villi) is obtained from the developing placenta between 10 and 12 weeks of pregnancy. The tissue is analyzed for chromosome disorders and, if indicated, specific genetic diseases.

On the positive side, CVS is performed much earlier in pregnancy than amniocentesis. On the negative side, CVS does not detect neural tube defects. However, an AFP test and a high resolution ultrasound examination can be performed later in pregnancy to screen for these defects.

How is CVS done?

An ultrasound examination is performed first to date the pregnancy and locate the developing placenta. The CVS sample can be obtained in two ways depending on the structure of the uterus and the position of the placenta. During transcervical CVS, a thin hollow tube is inserted through the vagina and cervix to reach the chorionic villi. Ultrasound is used to guide the tube to the edge of the developing placenta. A small amount of tissue is removed through the tube. Transabdominal CVS is similar to amniocentesis. Guided by ultrasound, a thin needle is inserted through the mother’s abdominal wall to obtain a small amount of chorionic villi. Both procedures usually take just a few minutes.

Does CVS hurt?

Some women say the procedure is uncomfortable. Most women are able to return to their regular activities the day after CVS.

Does CVS have any side effects?

Some women experience spotting, bleeding or cramping following CVS. These usually go away without difficulty. The following is recommended after undergoing CVS:

• No lifting over 15 pounds for 24 hours
• No strenuous exercise for 72 hours
• No air travel for 72 hours
• No sexual intercourse for 72 hours

There is a natural miscarriage rate throughout any pregnancy.