cvs test

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What is chorionic villus sampling?Chorionic villus sampling (CVS) is a prenatal test that detects chromosomal abnormalities such as Down syndrome, as well as a host of other genetic disorders. The doctor takes cells from tiny fingerlike projections on the placenta called the chorionic villi and sends them to a lab for genetic analysis.The main advantage of CVS over amniocentesis is that you can have it done earlier — generally between 11 and 12 weeks of pregnancy, although some testing centers will do it as late as 13 weeks. (For an amnio, you'll have to wait until you're at least 16 weeks pregnant.)Women who choose to have CVS or amniocentesis are primarily those at increased risk for genetic and chromosomal problems, in part because these tests

are invasive and carry a small risk of miscarriage. What kind of problems does CVS detect?Like amniocentesis, CVS can identify: • Nearly all chromosomal abnormalities, including Down syndrome, trisomy 13, trisomy 18, and sex chromosome abnormalities (such as syndrome and Klinefelter syndrome). The test is more than 99 percent accurate in diagnosing these conditions. • Several hundred genetic disorders, such as cystic fibrosis, sickle cell disease, and Tay-Sachs disease. The test is not used to look for all of them, but if your baby is at increased risk for one or more of these disorders, CVS can usually tell you whether he has the disease.Unlike amniocentesis, CVS cannot detect neural tube defects, such as spina bifida. If you

opt for CVS, you'll be offered a blood screening test in your second trimester to determine whether you're at increased risk for neural tube defects. Most neural tube defects can be detected by a detailed second-trimester ultrasound done at a state-of-the-art academic center.Be aware that if you have CVS, there's a 1 percent chance of getting a result called a mosaicism, in which some of the cell lines cultured from the placenta contain abnormal chromosomes and some are normal. If your CVS detects a mosaicism, you'll have to have amniocentesis and possibly other testing to determine whether your baby is affected. What factors would put me at increased risk of having a baby with a genetic abnormality or disorder?Some factors to consider include:Down syndrome screening resultsYou had a first trimester

screening or nuchal fold scan that indicated your baby is at a higher risk for Down syndrome or another chromosomal problem.Ultrasound resultsAn early ultrasound showed that your baby has structural defects associated with a chromosomal problem.r screening resultsYou and your spouse are both carriers of a recessive genetic disorder such as cystic fibrosis or sickle cell disease.Your historyYou've previously been pregnant with a child with a genetic abnormality and may be at a higher risk of this happening again.Your family historyYou or your partner has a chromosomal abnormality or genetic disorder or a family history that puts your child at

increased risk for genetic problems.Your ageAnyone can have a baby with a chromosomal abnormality, but the risk rises with the mother's age. For example, your likelihood of carrying a baby with Down syndrome ranges from about 1 in 1295 at age 20 to 1 in 82 at age 40.

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