chorionic villus sampling
Also known as chorionic villus biopsy, an invasive procedure
for prenatal diagnosis in which a sample of placental tissue (see placenta),
containing chorionic villi, is aspirated
through the cervix or abdomen under ultrasound
visualization. Chorionic villus sampling is usually performed between the
10th and 13th weeks of gestation. The cells so obtained are subject to chromosomal
analysis to determine if any abnormalities are present in the fetus.
This enables the diagnosis of chromosomal abnormalities such as Down's
See also amniocentesis.