Chorionic Villus Sampling (CVS)
CVS testing is used to diagnose chromosome problems or other genetic diseases in developing baby.
CVS testing is used to diagnose chromosome problems or other genetic diseases in developing baby. These include: Down syndrome (also called Trisomy 21), a condition in which a person has an extra chromosome or a piece of a chromosome. This extra copy changes how a baby's body and brain develop and can cause mental and physical challenges during their lifetime. Cystic fibrosis (CF), a disease that's inherited (passed down through families). It causes mucus buildup in the lungs and other organs, making it hard to breathe. Sickle cell disease (SCD), a group of inherited red blood cell disorders. SCD can cause pain, infections, organ damage, and strokes . Tay-Sachs disease , a disorder that causes fatty proteins to build up in the brain. It affects sight, hearing, and mental development. Most children with Tay-Sachs die by the age of 5. Trisomy 18 (Edward syndrome), a condition that causes the baby to have growth delays while developing. It also causes physical and mental abnormalities after they are born. Most babies with Trisomy 18 die before birth or within their first month. CVS testing is very accurate and can be done early in pregnancy, between the 10th and 13th week. But it can only diagnose certain genetic diseases. A CVS test does not diagnose or screen for birth defects such as neural tube defects . These are conditions that cause abnormal development of a developing baby's brain and/or spine. Different tests, including an alpha-fetoprotein (AFP) blood test , are used to screen for or diagnose these and other birth defects.
Why is this test ordered? A CVS test is not a routine pregnancy test. But your health care provider may recommend CVS testing if you are at higher risk for having a baby with a chromosome disorder. The risk factors include: Your age. If you are age 35 and older, you have a higher risk of having a baby with Down syndrome or another genetic disorder. A family history of a genetic disorder. Having another child with a genetic disorder. You may also need CVS testing if you had abnormal results on a prenatal screening test.
Clinical Interpretation
CVS test results are usually available within two weeks. If your CVS test results were normal , it is unlikely that your baby has the disorder that was tested. But it does not guarantee that your baby won't have any health problems. If your results were not normal , it may mean your baby has a chromosome or genetic disorder, such as Down syndrome or cystic fibrosis. Occasionally, CVS test results are unclear , and your provider may recommend amniocentesis . Amniocentesis is another prenatal diagnostic test that checks the amniotic fluid (the liquid in the sac surrounding the baby). It is performed between the 15th and 20th week of pregnancy. If you have questions about your results, talk to your provider.
Clinical Protocol & Patient Advice
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On the morning of the test, you may be asked to drink extra fluids and not urinate. This will fill your bladder, which may help move the uterus into a better position for the procedure.
Usage Guidance
- Reference ranges vary by laboratory. Always discuss your specific results with a qualified healthcare professional.
Source: MedlinePlus, National Library of Medicine. View the original.