chorionic villus sampling

(noun)

A form of prenatal diagnosis in which part of the placental tissue is tested for genetic abnormalities.

Related Terms

Examples of chorionic villus sampling in the following topics:

  • Prenatal Diagnostic Tests

    • ., amniocentesis (that can be done from about 14 weeks gestation up to about 20 weeks), and chorionic villus sampling (that can be done earlier: between 9.5 and 12.5 weeks gestation).
    • Chorionic villus sampling is associated with slightly more risk to the fetus.
    • Since chorionic villus sampling is performed earlier in the pregnancy than amniocentesis, typically during the first trimester, it can reasonably be expected that there will be a higher rate of miscarriage after chorionic villus sampling than after amniocentesis.
    • Because of the risk of miscarriage and fetal damage associated with amniocentesis and chorionic villus sampling procedures, many women prefer to first undergo screening so they can find out if the fetus' risk of birth defects is high enough to justify the risks of invasive testing.

  • Down Syndrome

    • Genetic counseling along with genetic testing, such as amniocentesis, chorionic villus sampling (CVS), or percutaneous umbilical cord blood sampling can be offered to families who may have an increased chance of having a child with Down syndrome, or where normal prenatal exams indicate possible problems.

  • Early Pregnancy Tests

    • Pregnancy tests are assays measuring indicators of pregnancy found in urine and blood samples, e.g., human chorionic gonadotropin (hCG).
    • Markers that indicate pregnancy are found in urine and blood: pregnancy tests require sampling one of these substances.
    • The first of these markers to be discovered, human chorionic gonadotropin (hCG), is produced by the trophoblast cells of the fertilized ovum (blastocyst).
    • Most chemical tests for pregnancy look for the presence of the beta subunit of hCG or human chorionic gonadotropin in the blood or urine. hCG can be detected in urine or blood after implantation, which occurs six to 12 days after fertilization.
    • Markers that indicate pregnancy are found in urine and blood: pregnancy tests require sampling one of these substances.

  • Fetal Circulation

    • Oxygen then diffuses from the placenta to the chorionic villus, an alveolus-like structure, from which it is carried to the umbilical vein.