Obstetrics• Updated 21 October 2026
Chorionic Villus Sampling (CVS)
A diagnostic test in early pregnancy that takes a small sample of the placenta to check the baby's chromosomes or genes.
Results: 1–2 weeks Specimen: Placental tissue
Quick Summary
Primary Purpose
To diagnose chromosomal or inherited conditions, such as thalassaemia, between 11 and 14 weeks.
What It Measures
Chromosomes or specific genes.
Preparation
Counselling beforehand.
Overview
CVS is done earlier than amniocentesis.
Used for families with thalassaemia or sickle cell risk.
What It Measures
Chromosomes or genes
As requested.
How It's Performed
- 01
Ultrasound guidance
To guide the needle.
- 02
Sample
Through the tummy or cervix.
- 03
Rest
For a day.
Interpreting Results & Next Steps
Discuss with Doctor
Your doctor will explain what your result means and what happens next.
If values are High:
Results confirm or rule out the condition.
Sources and further reading
Last updated 21 October 2026. For more detail, see these trusted health organisations.
- Chorionic Villus Sampling (CVS)(opens in a new tab) · MedlinePlus, US National Library of Medicine
- Chorionic villus sampling(opens in a new tab) · NHS