Chorionic Villus Sampling (CVS) is a prenatal test that can detect certain birth defects and genetic disorders in unborn babies. It involves taking a sample of chorionic villi cells from the placenta for testing. These cells have the same genes as the fetus.
Why People Get CVS:
- As a follow-up to noninvasive pregnancy testing (NIPT) if NIPT results indicate an elevated risk of certain chromosomal abnormalities.
- If there’s a family history of genetic disease.
- If the mother is 35 or older, as advanced maternal age increases the risk of genetic disorders.
- If there’s an existing child with a genetic disorder.
Conditions CVS Tests For Include:
- Down syndrome (trisomy 21)
- Trisomy 18
- Tay-Sachs disease
- Cystic fibrosis
- Sickle cell disease
- Turner syndrome
When CVS Is Done: It’s performed between the 10th and 13th weeks of pregnancy and is usually recommended based on risk factors.
CVS Procedure:
- Transcervical CVS: A catheter is inserted through the cervical opening into the uterus to collect samples.
- Transabdominal CVS: A thin needle is guided into the uterus through the abdomen using ultrasound imaging.
Possible Risks of CVS:
- Miscarriage (low risk, ranging from 0.2% to 1%)
- Infection (low risk)
- Preterm labor (uncommon)
- Rh sensitization (low risk)
- Limb deformity in babies (rare when performed too early, usually before 9 weeks)
- Leaking amniotic fluid
- Insufficient or inconclusive sampling
After CVS:
- Rest for about an hour.
- May experience mild cramping, discomfort, light spotting, or bleeding.
- Avoid strenuous activities for the first few days.
- Contact a healthcare provider if you experience heavy bleeding, contractions, fluid leakage, fever, or flu-like symptoms within 24 hours.
Getting Results:
- Lab examines the material taken during CVS.
- Results usually available in 7 to 14 days.
- CVS testing is about 99% accurate but doesn’t determine the severity of conditions.
- Healthcare provider guides further steps based on results, which may include medication, surgery, or counseling.
CVS vs. Amniocentesis:
- CVS can be done earlier (10-13 weeks) than amniocentesis (at least 15 weeks).
- Amniocentesis tests for neural tube defects like spina bifida, which CVS doesn’t.
CVS and amniocentesis are more invasive than NIPT but offer higher accuracy for genetic abnormalities detection. Parents have more time for decisions with CVS due to its earlier timing.