More than 27,000 women have sought the CVS expertise of John Williams, III, MD, director of Reproductive Genetics at Cedars-Sinai. CVS, or chorionic villus sampling, is a less invasive alternative to amniocentesis for prenatal diagnosis of genetic disorders and chromosome abnormalities—and can be performed six to eight weeks earlier in a pregnancy. Dr. Williams’ name is nearly synonymous with CVS, as he has performed the test more often than any other practitioner west of the Mississippi.