CHORIONIC VILLUS SAMPLING (CVS)

CVS can be performed earlier in pregnancy than a genetic amniocentesis.  It is usually performed at 10 – 12 weeks after the last menstrual period.  This allows for earlier detection of chromosomal abnormalities.

When CVS is performed, a small sample of cells is taken from the placenta where it attaches to the wall of the uterus.  Chorionic villi are tiny parts of the placenta, formed from the fertilized egg.  Therefore, they have the same genes as the fetus.  An ultrasound is also performed with CVS.

To collect the sample, a speculum is inserted as it would be for a Pap test.  Then, a very thin, plastic tube is inserted through the vagina and into the cervix.  With ultrasound, the tube is guided to the placenta and a small sample is removed.  The sample is then sent to the lab for genetic testing.  Occasionally, the sample must be obtained by inserting a needle through the abdominal wall.  This decision cannot be made until the time of your appointment.  This will be discussed with you before any procedure is performed.  This procedure usually takes 45 minutes to complete.