Chorionic villus sampling

• In transabdominal CVS (shown on the left), the doctor inserts a needle straight into the belly to take a sample of the placenta, which is also called the "chorionic villus."
• In transcervical CVS (shown on the right), the doctor inserts a tube through the vagina to take the sample of placenta.

In both ways, the doctor uses ultrasound images to guide where the tube or needle goes.