Chorionic Villus Sampling (CVS)
One of the prenatal testing techniques available is chorionic villus sampling, or CVS for short. This type of genetic testing is used to determine chromosomal or genetic abnormalities early on in pregnancy by taking a tissue sample of the chorionic villi from the placenta. The chorionic villi are tiny finger-like projections of the placental tissue which contain the same genetic material as the fetus. CVS is usually performed 10-12 weeks into the pregnancy.
This procedure usually takes place in a doctorâ€™s office or hospital. There are two options for obtaining the chorionic villus sample, a transabdominal CVS or transcervical CVS. During a transabdominal CVS, the doctor uses ultrasound to identify a prime sampling area and then directs the needle to the correct location. The long hollow needle is then inserted through the abdomen and placed between the uterus and the placenta. A transcervical CVS is very similar to a transabdominal CVS. During this procedure, the doctor will use an ultrasound to guide the catheter through the vagina and then into the uterus to the correct region of the placenta. After the sample is taken, the chromosomes of the fetus are examined through karyotyping. Karyotyping involves staining the 46 chromosomes and rearranging them into 23 pairs to observe any abnormalities. CVS is about 99% accurate and carries an approximately 1% risk of miscarriage.
CLICK HEREÂ for an introduction to genetic testing
CLICK HEREÂ for an introduction to ultrasound and protein markers
CLICK HEREÂ for an introduction to amniocentesis
CLICK HEREÂ for an introduction to cell-free fetal DNA
CLICK HERE for a case study that asks if amniocentesis or CVS is a better choice for an early pregnancy with signs of a problem