415.202.1200
One Daniel Burnham Court, Suite 230C San Francisco, California 94109
Our Services
CVS
What is CVS?
Chorionic villus sampling (CVS) is a prenatal diagnostic procedure performed between 10 weeks, 0 days to 12 weeks, 6 days of pregnancy. During the procedure, a small amount of tissue from the placenta (called chorionic villi) is taken. The cells from the chorionic villi are then analyzed in a lab to look for specific chromosome and/or genetic disorders.
Who should consider CVS?
Previous recommendations stated that women who are 35 years or older at the time of delivery should consider CVS. However, in 2007 the American College of Obstetricians and Gynecologists (ACOG) released new recommendations stating the following.
- All women regardless of age should have the option of diagnostic testing, such as CVS
Additionally, CVS should be considered for the following:
- Women who have had a positive first trimester screening result such as Combined First Trimester screening
- Couples in which one partner carries a chromosome rearrangement, such as a translocation.
- Couples with a family history of a chromosome abnormality.
- Couples at increased risk of having a child with a testable genetic disease.
What can CVS detect?
- Chromosome abnormalities such as Down syndrome.
- Specific known genetic conditions in a family, such as cystic fibrosis (CF).
It is important to remember that although CVS is considered diagnostic, results cannot detect all birth defects, genetic conditions, or types of mental retardation.
How is CVS Performed?
You will meet with a genetic counselor before the procedure to obtain a thorough genetic history. An ultrasound examination will be performed to confirm the date of the pregnancy and to locate the placenta. CVS can be performed one of two ways depending upon where the placenta is located.
- Transabdominal CVS: Under ultrasound guidance, the physician guides a thin needle through the abdomen and into the placenta. A very small amount of tissue is obtained and the tissue is then sent to the lab for analysis.
- Transcervical CVS: Under ultrasound guidance, the physician places a catheter, which is a thin hollow tube, through the vagina and cervix and then guides the catheter to the outer edge of the placenta. A very small amount of tissue is obtained and then sent to the lab for analysis.
What, if any, preparations are necessary before the procedure?
Women should refrain from taking aspirin or aspirin-containing products for 5 days before the procedure. Heparin should also be discontinued for 24 hours before the procedure.
A full bladder is required for the ultrasound portion of the appointment. Instructions on how much water to drink will be provided prior to the appointment.
What are the recommendations after CVS?
After the procedure, it is important go home and rest for the remainder of the day.
Additionally, we advise:
- No lifting over 15 pounds for 24 hours.
- No exercise, intercourse, or travel by plane for 48 hours (2 days).
What are the risks?
The procedure-related risk associated with CVS is thought to be the same as for amniocentesis; less than 1 in 400. While there is absolute consensus on the rate of miscarriage due to CVS in the United States, the physician's skill and experience may also play an important role. The physicians who perform CVS at San Francisco Perinatal Associates, perform a large number of CVS procedures each year and have had many years of experience performing these procedures. The majority of women experience little to no complications after CVS. Minor complications might include spotting or light bleeding, and/or cramping.
When are CVS results available?
Chromosome results are typically ready about 7-10 days after the procedure. Studies which look for specific genetic conditions may take longer. Also, there is a 1% to 2% chance that the results from CVS will be inconclusive. In these cases, amniocentesis (a diagnostic test performed between 16-20 weeks of pregnancy) may be needed to clarify the results.
To schedule CVS, please contact San Francisco Perinatal Associates at 415-202-1200 and we will be happy to assist you. Should you have additional questions about CVS, please feel free to call and speak with one of our genetic counselors.
