INVASIVE PROCEDURES
CHORIONIC VILLUS SAMPLING
Chorionic villus sampling (CVS) is a diagnostic outpatient office procedure
performed under ultrasound (U/S) guidance without anesthesia. Pregnancy loss
rate is 0.7%.
The catheter is placed directly into the placental tissue without entering the
amniotic cavity. Chorionic villi, which are placental precursors, are aspirated
from a pregnant uterus between 10 and 12 weeks’ gestation.
The tissue is sent to the laboratory for karyotyping. The chromosomes of the
villi are almost always identical to those of the embryo.
The procedure can be performed either transcervically or transabdominally.
Since the fetus and chorionic villi are both derived from a common origin (the
zygote), their karyotype is identical more than 99% of the time.http://ebookobgyne.net