chorionic villus sampling definition of chorionic villus sampling in the Free Online Encyclopedia.

chorionic villus sampling (CVS) or chorionic villus biopsy (CVB) (kōr'ē-ŏn`ĭk, kôr'–), diagnostic procedure in which a sample of chorionic villi from the developing placenta is removed from the uterus of a pregnant woman (see pregnancy pregnancy, period of time between fertilization of the ovum (conception) and birth , during which mammals carry their developing young in the uterus (see embryo ). The duration of pregnancy in humans is about 280 days, equal to 9 calendar months.
..... Click the link for more information. ) using a fine needle inserted through the abdomen or a thin plastic catheter inserted into the vagina and through the cervix. Chorionic villi are fingerlike projections of a membrane (the chorion) that surrounds the fetus. The villi develop from the fertilized ovum ovum (ō`vəm), in biology, specialized plant or animal sex cell, also called the egg, or egg cell.
..... Click the link for more information. , or egg, and have a genetic composition similar to that of the fetus. Cells in the sample are grown in the laboratory and studied to detect the presence in the fetus of such genetic birth defects birth defects, abnormalities in physical or mental structure or function that are present at birth. They range from minor to seriously deforming or life-threatening. A major defect of some type occurs in approximately 3% of all births.
..... Click the link for more information. as Tay-Sachs disease Tay-Sachs disease (tā`-săks`)
..... Click the link for more information. and Down syndrome Down syndrome, congenital disorder characterized by mild to severe mental retardation , slow physical development, and characteristic physical features. Down syndrome affects about 1 in every 730 live births and occurs in all populations equally.
..... Click the link for more information. . The sex of the child can also be ascertained. Although CVS tests for the same range of abnormalities as amniocentesis amniocentesis (ăm'nēō'sĕntē`sĭs)
..... Click the link for more information. , it is usually performed some weeks earlier (between the 8th and 12th weeks of pregnancy), and the results are available in a few days. It is recommended if the parents are carriers of certain genetic diseases, if there is a family history of genetic disorders, or if the woman is over age 35 (later pregnancies carrying with them a higher risk of chromosomal abnormality).