Chorionic villous sampling in pregnancy, Medical staff carrying out chorionic villous sampling (CVS) on a pregnant woman, An ultrasound transducer has been used to guide the needle and syringe being used, The uterus, foetus and needle are seen on the ultrasound scan on the screen in the background, The foetal chorionic villi tissue, in the mother's placenta, contains foetal blood vessels and is a way of obtaining foetal blood, Chorionic villus sampling is usually conducted between 9 and 12 weeks of pregnancy to evaluate the chromosomal and DNA (deoxyribonucleic acid) status of the foetus, It is a way of diagnosing foetal abnormalities in early pregnancy,