What It Is
Chorionic villus sampling, commonly abbreviated as CVS, is a procedure performed during pregnancy that involves collecting a small sample of placental tissue for genetic and chromosomal testing.
What It Checks
The placental tissue sampled during CVS shares the same genetic material as the developing baby, since it develops from the same fertilized egg. This allows the sample to be analyzed for certain genetic and chromosomal conditions, similar in purpose to amniocentesis, but performed earlier in pregnancy.
Why It's Used
CVS is commonly used when there's an increased likelihood of a genetic or chromosomal condition, often based on earlier screening results, maternal age, or family history, and is generally chosen over amniocentesis when earlier diagnostic results are preferred, since it can be performed at an earlier stage of pregnancy.
How It's Done
CVS can be performed in one of two ways: through the abdomen, using a thin needle guided by ultrasound, similar in approach to amniocentesis, or through the cervix, using a thin tube. In both approaches, a small sample of placental tissue, called chorionic villi, is collected and sent to a laboratory for detailed genetic analysis.
Background
Chorionic villus sampling was developed in the late 1960s and refined considerably through the 1970s and 1980s, offering an alternative to amniocentesis that could be performed earlier in pregnancy, providing earlier diagnostic information for those who wanted it. The technique has continued to be refined for safety and accuracy since its introduction, and it remains an established diagnostic option in prenatal genetic testing today.