Chorionic Villus Sampling is a medical investigation used for diagnostic screening or as a means of sample collection for prenatal paternity test The test can be performed between the 10-12th week of pregnancy (slightly earlier than amniocentesis) and involves the insertion of a needle through the abdomen or through the cervix in order to withdraw a sample of chorionic villi. Chorionic villi are structures which line the placenta in order to increase surface area and maximize contact with the mother’s blood. The test carries certain risks including miscarriage, infection or leakage of amniotic fluid. The Sample collected is rich in fetal DNA which can be used for a prenatal paternity test. The risks do however, discourage some from undertaking this sampling to establish paternity. Today, non invasive prenatal paternity tests are available which can be done with a simple medical blood draw which means chorionic villus sampling can be avoided to determine paternity. Although non invasive prenatal paternity testing is available and risk free, it is always worth considering the option of post natal testing. The sampling is always more sample and straightforward in a post natal test. Read more about sampling after the birth of the child should you be considering this option. If you are considering a prenatal test with chorionic villus sampling, all the risks and procedure entailed will be fully explained by an OBGYN.