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: 06/05/2010
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of
Physician Assistant Studies, University of Washington, School of
Medicine; Susan Storck, MD, FACOG, Chief, Eastside Department of
Obstetrics and Gynecology, Group Health Cooperative of Puget Sound,
Redmond, Washington; Clinical Teaching Faculty, Department of
Obstetrics and Gynecology, University of Washington School of
Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director,
A.D.A.M., Inc.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)
