
The chorion is the portion of fetal membrane that eventually forms the fetal side of the placenta. The chorion contains chorionic villi, which are small finger-like projections. These villi are snipped or suctioned off for study in the procedure. Since the chorionic villi are of fetal origin, examining samples of them can provide the genetic makeup of the fetus. This test is performed to identify congenital defects. Experts use the sample to study the DNA, chromosomes, and enzymes of the fetus. The test can be done before amniocentesis, about 10 to 12 weeks after a missed period.

Review Date:9/19/2006
Reviewed By:Audra Robertson, MD, Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Boston, MA. Review provided by VeriMed Healthcare Network.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is the first of its kind, requiring compliance with 53 standards of quality and accountability, verified by independent audit. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial process. A.D.A.M. is also a founding member of Hi-Ethics (www.hiethics.com) and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).
The Agency for Health Care Administration (Agency) and this website do not claim the information on, or referred to by, this site is error free. This site may include links to websites of other government agencies or private groups. Our Agency and this website do not control such sites and are not responsible for their content. Reference to or links to any other group, product, service, or information does not mean our Agency or this website approves of that group, product, service, or information.
Additionally, while health information provided through this website may be a valuable resource for the public, it is not designed to offer medical advice. Talk with your doctor about medical care questions you may have.