Chorionic villus sampling. Doctor's hand holds an ultrasound emitter (white) onto a woman's pregnant abdomen while drawing a chorionic villus sample into a syringe. On ultrasound screens in the back- ground, the womb of the pregnant woman is seen. The ultrasound imaging enables the needle to be directed to chorionic villi tissue of the foetus which is found in the mother's placenta. Chorionic villi contain foetal blood vessels and is a way of obtaining foetal blood. Chorionic villus sampling (CVS) is usually conducted between 9-12 weeks of pregnancy to evaluate the chromosomal and DNA status of the foetus. CVS is a way of diagnosing abnormalities in a foetus in early pregnancy.