BACK TOTOP Browse A-ZSearchBrowse A-ZABCDEFGHIJKLMNOPQRSTUVWXYZ0-9 E-mail FormEmail ResultsName:Email address:Recipients Name:Recipients address:Message: Print-FriendlyBookmarksbookmarks-menuChorionic villus samplingCVS; Pregnancy - CVS; Genetic counseling - CVSChorionic villus sampling (CVS) is a test some pregnant women have to screen their baby for genetic problems. How the Test is Performed CVS can be done through the cervix (transcervical) or through the belly (transabdominal). Miscarriage rates are slightly higher when the test is done through the cervix.The transcervical procedure is performed by inserting a thin plastic tube through the vagina and cervix to reach the placenta. Your health care provider uses ultrasound images to help guide the tube into the best area for sampling. A small sample of chorionic villus (placental) tissue is then removed.The transabdominal procedure is performed by inserting a needle through the abdomen and uterus and into the placenta. Ultrasound is used to help guide the needle, and a small amount of tissue is drawn into the syringe.The sample is placed in a dish and evaluated in a lab. Test results take about 2 weeks. How to Prepare for the Test Your provider will explain the procedure, its risks, and alternative procedures such as amniocentesis.AmniocentesisAmniocentesis is a test that can be done during pregnancy to look for certain problems in the developing baby. These problems include:Birth defectsG...ImageRead Article Now Book Mark Article You will be asked to sign a consent form before this procedure. You may be asked to wear a hospital gown.The morning of the procedure, you may be asked to drink fluids and refrain from urinating. Doing so fills your bladder, which helps your provider see where to best guide the needle.Tell your provider if you are allergic to iodine or shellfish, or if you have any other allergies. How the Test will Feel The ultrasound does not hurt. A clear, water-based gel is applied to your skin to help with the transmission of the sound waves. A hand-held probe called a transducer is then moved over your belly area. In addition, your provider may apply pressure on your abdomen to find the position of your uterus.The gel will feel cold at first and may irritate your skin if not washed off after the procedure.Some women say the vaginal approach feels like a Pap test with some discomfort and a feeling of pressure. There may be a small amount of vaginal bleeding following the procedure.Pap testThe Pap test checks for cervical cancer. Cells scraped from the opening of the cervix are examined under a microscope. The cervix is the lower part...ImageRead Article Now Book Mark Article An obstetrician can perform this procedure in about 5 minutes, after preparation. Why the Test is Performed The test is used to identify any genetic disease in your unborn baby. It is very accurate, and it can be done very early in a pregnancy.Genetic problems can occur in any pregnancy. However, the following factors increase the risk:An older mother Past pregnancies with genetic problems Family history of genetic disordersGenetic counseling is recommended before the procedure. This will allow you to make an unhurried, informed decision about options for prenatal diagnosis.Genetic counselingGenetics is the study of heredity, the process of a parent passing certain genes on to their children. A person's appearance, such as height, hair co...ImageRead Article Now Book Mark Article CVS can be done sooner in pregnancy than amniocentesis, most often at about 10 to 12 weeks.CVS does not detect:Neural tube defects (these involve the spinal column or brain) Rh incompatibility (this occurs when a pregnant woman has Rh-negative blood and her unborn baby has Rh-positive blood) Rh incompatibilityRh incompatibility is a condition that develops when a pregnant woman has Rh-negative blood and the baby in her womb has Rh-positive blood.ImageRead Article Now Book Mark Article Birth defects Issues related to brain function, such as autism and intellectual disability Normal Results A normal result means there are no signs of genetic defects in the developing baby. Even though the test results are very accurate, no test is 100% accurate at testing for genetic problems in a pregnancy. What Abnormal Results Mean This test can help detect hundreds of genetic disorders. Abnormal results may be due to many different genetic conditions, including:Down syndrome Down syndromeDown syndrome is a genetic condition in which a person has 47 chromosomes instead of the usual 46.Read Article Now Book Mark Article Hemoglobinopathies HemoglobinopathiesHemoglobinopathy is a group of disorders in which there is abnormal production or structure of the hemoglobin molecule. It is passed down through fa...Read Article Now Book Mark Article Tay-Sachs diseaseTay-Sachs diseaseTay-Sachs disease is a life-threatening disease of the nervous system passed down through families.ImageRead Article Now Book Mark Article Talk to your provider about the meaning of your specific test results. Ask your provider:How the condition or defect may be treated either during or after the pregnancy What special needs your child may have after birth What other options you have about maintaining or ending your pregnancy Risks The risks of CVS are only slightly higher than those of amniocentesis.Possible complications include:Bleeding Infection Miscarriage (in up to 1 in 100 women) Rh incompatibility in the mother Rupture of membranes which may lead to miscarriage Considerations If your blood is Rh negative, you may receive a medicine called Rho(D) immune globulin (RhoGAM and other brands) to prevent Rh incompatibility.You will receive a follow-up ultrasound 2 to 4 days after the procedure to make sure your pregnancy is proceeding normally.Open ReferencesReferencesCheng EY. Prenatal diagnosis. In: Gleason CA, Juul SE, eds. Avery's Diseases of the Newborn. 10th ed. Philadelphia, PA: Elsevier; 2018:chap 18.Driscoll DA, Simpson JL. Genetic screening and diagnosis. In: Landon MB, Galan HL, Jauniaux ERM, et al, eds. Gabbe's Obstetrics: Normal and Problem Pregnancies. 8th ed. Philadelphia, PA: Elsevier; 2021:chap 10.Wapner RJ, Dugoff L. Prenatal diagnosis of congenital disorders. In: Resnik R, Lockwood CJ, Moore TR, Greene MF, Copel JA, Silver RM, eds. Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2019:chap 32.AllVideoImagesTogChorionic villus sampling - illustration 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.Chorionic villus samplingillustrationChorionic villus sampling - normal anatomyPresentation Chorionic villus sampling - illustration 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.Chorionic villus samplingillustration Chorionic villus sampling - normal anatomyPresentation Tests for Chorionic villus sampling Chorionic villus samplingRelated Information Amniocentesis(Medical Test)Rh incompatibility(Condition)Biopsy(Medical Test)Tay-Sachs disease(Condition) Review Date: 12/3/2020 Reviewed By: LaQuita Martinez, MD, Department of Obstetrics and Gynecology, Emory Johns Creek Hospital, Alpharetta, GA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. 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