More research is needed on the best surgical instruments to use for chorionic villus sampling testing during early pregnancy. Chorionic villus sampling (CVS) is a test where a small piece of chorion (placental tissue) is removed from the woman's uterus and used for genetic testing. Chorion can be removed through the abdomen or through the cervix using fine needles, plastic or metal tubes or biopsy forceps. The woman's risk of miscarriage increases if several attempts are needed to get chorion, or the gestational sac is damaged. The review found some evidence that small forceps may be more effective and less painful than aspiration cannulae for transcervical CVS. There were no trials found on transabdominal CVS.