Chorionic villus sampling (CVS) is a diagnostic test usually performed between 11-14 weeks of pregnancy. This test will provide you with a definitive (yes or no) assessment about chromosome disorders in the pregnancy, such as Down syndrome. This test can also test for some other genetic disorders for pregnancies considered to be at an increased risk.
Using high-resolution ultrasound for guidance, the physician will either insert a needle through your abdomen or will insert a small catheter through the cervix to the placenta (depending on the location of the placenta). A small sample of chorionic villi (cells from the placenta) is removed to complete the testing.
Chorionic villus sampling is performed earlier in the pregnancy than amniocentesis, so results are returned sooner. However, a CVS is unable to test for open neural tube defects, such as spina bifida. However, testing can be completed with a simple blood test in the second trimester where they measure a protein in your blood called AFP. Open neural tube defects can also be screened for during your anatomy scan around 20 weeks of pregnancy.
Preliminary results will be available 2 to 3 days after your procedure. Final results will be ready 10 to 14 days following your CVS. Results occasionally take longer. If you do not have your results in fourteen days from the procedure, feel free to contact us. When calling, please be sure to leave phone numbers where you can be reached late in the day.
Genetic counseling is recommended to anyone considering CVS or any prenatal testing.
Some of the most common reasons patients consider undergoing chorionic villus sampling are:
- Age 35 or older at delivery
- A previous child with a chromosome abnormality or an identified genetic disorder
- A parent carries a balanced chromosome translocation (rearrangement)
- Both parents are carriers for the same genetic disease (for example: Tay-Sachs, sickle cell anemia, and many others for which we have genetic testing available)
- An abnormal First Trimester Screen or cell-free DNA screening (also known as NIPT) indicating that the pregnancy is at an increased risk for a chromosome disorder
- Finding of a fetal abnormality on ultrasound