Information on Chorionic Villus Sampling (CVS)
Facts About this Prenatal Diagnosis Test
Jun 30, 2009
Medline Plus's online Medical Encyclopedia defines CVS as "the removal of a small piece of placenta tissue (chorionic villi) from the uterus during early pregnancy to screen the baby for genetic defects."
This test is sometimes ordered for women whose children are at a high risk of inheriting serious genetic health problems, or for pregnant women who are at a higher risk of having children with health problems due to other factors as determined by the attending physician. This test may also be ordered for women over the age of 35, particularly if they have a family history of serious heritable diseases.
CVS Facts:
- CVS is generally performed 10-12 weeks after the woman's last menstruation, during the first trimester.
- The tissue sample will be collected either through the cervix or through the abdomen.
- The test will examine the fetus's DNA, chromosomes, and enzymes.
- The entire procedure typically takes about 20 minutes.
- Women typically receive an ultrasound 2-4 days after the test to check for continued healthy development of the baby.
- CVS has been used for prenatal diagnosis since the mid-1980s.
CVS Results:
Results typically take less than 2 weeks to be delivered. CVS does not generally detect potential physical developmental problems, including limb underdevelopment or neural tube defects. A normal result does not necessarily mean the child will have no genetic health issues.
Results indicating a genetic or chromosomal problem is or is not present are typically about 98% accurate. Abnormal results may potentially be supported or refuted by amniocentesis later in the pregnancy. Detection of a genetic problem does not speak to the severity of the disease.
CVS Risks:
There is typically minor post-CVS vaginal bleeding, with a very fast recovery period. In rare instances, complications may include excessive vaginal bleeding or discharge and fever. Miscarriages, physical damage to the baby, infection, and Rh incompatibility problems may occur very rarely.
CVS Benefits:
- Allows early detection of potential serious health problems so that the pregnant woman can prepare herself in advance for the possibility of having a disabled child.
- Early detection may allow early (even in utero) treatment of the problem, as with spina bifida.
Chorionic Villus Sampling vs Amniocentesis
CVS is the most common invasive prenatal diagnostic procedure performed during the first trimester of a pregnancy.
Though the risks of CVS are slightly higher than the potential risks from amniocentesis, CVS has the advantage of being available considerably earlier during a pregnancy. Results from CVS are typically returned more quickly than those of amniocentesis.
Additional Sources for CVS Information:
Embryo Project Encyclopedia: Chorionic Villus Sampling
Lane, Brenda: CVS - Chorionic Villus Sampling
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