What is CVS?

Chorionic Villus Sampling (CVS) is a diagnostic procedure that takes a small sample of chorionic villi — tissue from the developing placenta, which shares the baby's genetic material — for chromosomal and genetic analysis. Its main advantage over amniocentesis is timing: it can be performed earlier in pregnancy.

Why is CVS done?

  • To confirm a chromosomal condition earlier than amniocentesis would allow, when screening (NT scan, combined screening, or NIPT) suggests a higher risk
  • When parents want a definitive answer as early as possible in the pregnancy
  • To test for specific genetic conditions known to run in the family

When is it done?

CVS is typically performed between 11 and 13 weeks and 6 days of pregnancy — earlier than amniocentesis.

How to prepare

Preparation is minimal. Dr. Chandak will advise on bladder preparation depending on the exact approach used on the day. Mention any blood-thinning medicines or bleeding disorders beforehand.

What happens during the procedure

Most commonly, a fine needle is passed through the abdomen under continuous ultrasound guidance to reach the placental tissue, and a small sample is withdrawn. The procedure usually takes 10 to 20 minutes.

What happens after

Rest is recommended for the rest of the day. Mild cramping or light spotting is common. Results typically take one to two weeks, with a rapid preliminary result for common conditions often available sooner.

Is CVS safe?

Possible risks CVS carries a small procedural risk of miscarriage, generally cited in the range of 0.5% to 1% — slightly higher than amniocentesis, reflecting the earlier stage of pregnancy at which it's performed. Dr. Chandak will discuss your individual risk before you decide whether CVS is right for you.

Frequently asked questions

Both are diagnostic tests giving a definitive answer on chromosomal conditions. The main difference is timing — CVS is done earlier (11–13+6 weeks) by sampling placental tissue, while amniocentesis is done later (15–20 weeks) by sampling amniotic fluid.

CVS carries a slightly higher procedural miscarriage risk than amniocentesis, generally cited around 0.5–1% versus 0.5%. Dr. Chandak will discuss what this means for your specific situation.

Some parents prefer the earlier certainty CVS provides, particularly when a screening result has raised concern early in pregnancy.

A rapid preliminary result is often available within a few days; full results typically take one to two weeks.