Chorionic Vili Sampling

A prenatal diagnostic test that detects chromosomal abnormalities in a fetus. It involves the villi (hairlike projections) that compose the chorion (the outer layer of the amniotic fluid. A CVS test can be performed between the 9th and the 12th of pregnancy, providing earlier diagnosis than amniotic fluid studies.

REASONS FOR PROCEDURE

  • Mother is over age 35.
  • Pregnancy is considered high-risk.
  • A blood test (AFP and triple screen) has suggested increased risk for chromosome abnormality.
  • Mother has previously had a child with chromosome abnormality, such as Down Syndrome.

RISK
None expected.

DESCRIPTION OF PROCEDURE

  • Ultrasound is used to determine the location of the fetus.
  • In one technique used, an anesthetic is injected into the abdominal skin and then a long hollow needle is inserted into the abdomen to withdraw the villi.
  • The second technique is done through the vagina. A catheter is inserted through the cervix into the uterus, and suction is applied to pull the villi into the catheter which is then removed.

EXPECTED OUTCOME
You should experience no follow-up discomfort. Test results should be available within 1-2 weeks.

POSSIBLE COMPLICATIONS

  • In some cases, insufficient villi are obtained and the needle or catheter must be reinserted.
  • Slight risk of a miscarriage (1-2%).
  • Excessive bleeding (rare).
  • Risk of infection.

POSTPROCEDURE CARE
GENERAL MEASURES
Bathe or shower as usual.

MEDICATION
Medication is usually not necessary following this procedure.

ACTIVITY
No restrictions.

DIET
No special diet.