John Williams, III MD, director, Reproductive Genetics, discusses the chorionic villus sampling procedure.
CVS is a procedure in which a small amount of placental tissue is removed during the 10th to 13th week of pregnancy for genetic testing. Chorionic villi tissue originates from the same fertilized egg as the fetus and contains the same genetic data as the fetus. These cells can be analyzed for many fetal genetic disorders before birth.
The Prenatal Diagnosis Center is the most experienced and largest facility for chorionic villus sampling in the nation performing approximately 2,000 procedures per year. Dr. John Williams III, highly respected nationwide for his expertise, has performed more than 27,000 CVS procedures.
Genetic counseling is provided before each CVS procedure. Our genetic counselors work closely with the physicians and are an invaluable part of ensuring that patients have a positive CVS experience. The counselors provide a complete family history evaluation, and they provide information to help families decide if the procedure is right for them. They also help families cope with abnormal results.
There are two ways to perform CVS - transcervical and transabdominal. The type that is right for you will depend on the number of fetuses, the position of your uterus and the location of your placenta within the uterus. Both approaches include a detailed ultrasound examination.
Testing Prior to CVS
Patients referred for CVS should have the following tests performed and should have all results sent to the CVS provider:
Prenatal panel (blood) and Chlamydia, Gonorrhea, and Group B Strep tested at their obstetrician's office two weeks prior to their procedure.
In order to have a Chorionic Villi Sampling (CVS) procedure, we will need labs and cultures results faxed to our office before the date of your procedure.
Please click here to view or print the Chorionic Villi Sampling form .
Candidates for CVS
CVS is discussed as an option for prenatal diagnosis for many reasons. The most common reasons are:
- A woman is 35 or older at the time of delivery
- Family history of an inherited genetic disorder (chromosomal or others)
- Increased risk of chromosomal abnormalities based on first trimester screening methods
- Fetal abnormality seen with first trimester ultrasound
- Parents who have a child with Down Syndrome or other genetic disorder
Fetal sex selection is not an indication for CVS except in rare cases of gender-related genetic disorders.
Diagnostic results from CVS are available earlier than other methods of prenatal diagnosis. Amniocentesis, by comparison, is not generally performed until at least 15 weeks with results available two weeks later. Results from CVS are available by the 10th to 13th week of pregnancy, usually before a woman begins showing or feels fetal movement. This provides more privacy and possibly less emotional distress with regard to decisions about continuing the pregnancy.
Preliminary chromosome results are available two to four business days after the procedure. Final chromosome results are available in 12 to 14 days. Other genetic tests may take longer, depending on type and the need for an outside laboratory.
Risks of CVS
When performed by an experienced physician, CVS is a safe procedure. CVS-related complications and miscarriage occur about 0.5% more often then the natural miscarriage rate of one in 50 pregnancies. Other minor problems such as vaginal bleeding (spotting) or mild cramping are reported to occur more often after CVS than amniocentesis.
Post CVS Instructions
We have prepared an instruction sheet that describes the steps you will go through after the procedure. You can read or print the POST-CVS INSTRUCTIONS here.
To schedule an appointment
Toll Free: (800) CEDARS-1 or (800) 233-2771