Chorionic Villus Sampling

What is Chorionic Villus Sampling?

Chorionic Villus Sampling is another prenatal diagnostic test used to determine if a fetus has any genetic abnormalities. Like the amniocentesis, the test is done early in pregnancy, but some people prefer it to amniocentesis because it can be performed as early as 10 weeks , typically between 10 and 13 weeks (amniocentesis is done between 14-20 weeks) and the results typically come back in about 7-10 days (results for amniocentesis can take up to 4 weeks).

What is the Chorionic Villi?

Chorionic villi are tiny finger-shaped growths found in the placenta. The genetic material in chorionic villus cells is the same as that in the baby’s cells so they can be analyzed and information about the baby can be obtained.

Who is recommended for Chorionic Villus Sampling?

Women at an increased risk for genetic abnormalities are recommended to have prenatal diagnostic screening. Many couples  choose chorionic villus sampling over amniocentesis because it can be performed earlier in the pregnancy. Additionally, if significant genetic abnormalities are found, many couples elect to terminate the pregnancy and this is easier and safer earlier in pregnancy. Indications for chorionic villus sampling are the same as for amniocentesis.

How is Chorionic Villus Sampling Performed?

Chorionic villus sampling is done by first visualizing the fetus and placenta on ultrasound. Making sure that the fetus and placenta are not in any danger of injury, the Obstetrician then puts  a thin flexible tube (catheter) through the vagina and cervix into the placenta and a small amount of tissue is removed. The sample is then sent to the lab for analysis which takes about 1 to 2 weeks. The sample can also be collected through a long, thin needle put through the belly into the placenta.

What are the potential complications of Chorionic Villus Sampling?

The most significant complication of chorionic villus sampling is miscarriage. Since miscarriage is more common in early pregnancy, an invasive diagnostic procedure such as chorionic villus sampling which tampers with the developing placenta can increase this risk. Other less serious side effects are cramping, pain at the puncture site (if done as an abdominal procedure), vaginal spotting and infection.

Image from Byer/Shainberg/Galliano Dimensions of Human Sexuality 5th edition Copyright 1999 The McGraw Hill Companies, Inc. All Rights Reserved.