Chorionic Villus Sampling ( CVS )
CVS is used to identify chromosomal problems, such as Down syndrome. It can also detect other genetic diaeases. The main advantage of CVS over amniocentesis is it done much earlier in pregnancy, at 10 to 12 weeks, rather than 15 to 20 weeks.
CVS is performed by taking a tiny piece of tissue from the chorionic villi. Under ultrasound guidance, the tissue is obtained either with a needle through the abdomen or a catheter inserted through the cervix. The tissue is then cultured and a karyotype analysis i.e. analysis of the chromosomal make-up of the cells is performed. It takes about 2 to 3 weeks to receive the results.