chorionic villus sampling (CVS) [Gk, chorion, skin + L, villos, shaggy hair + L, exemplum, example] , the sampling of placental tissues for prenatal diagnosis of potential genetic defects. The sample is obtained through a catheter inserted into the cervix. One of the main advantages of having this test instead of amniocentesis is that it can be done earlier in pregnancy. Also called chorionic villus biopsy, CVB. Compare amniocentesis.
