This page will give you information about chorionic villus sampling. If you have any questions, you should ask your GP or other relevant health professional.
What is chorionic villus sampling?
Chorionic villus sampling (CVS) involves using a needle to remove some tissue from the placenta. The cells in the placenta are similar to your baby’s cells. CVS is usually performed between 11 and 13 weeks of pregnancy.
CVS can help find out if your baby has one of the following problems.
- A chromosome disorder such as Down’s syndrome.
- A genetic or hereditary disease such as cystic fibrosis or sickle cell anaemia.
However, CVS does not cover all possible problems and the results may sometimes be wrong. CVS does not show if your baby has a neural tube defect such as spina bifida.
Figure 1 - Chorionic Villus Sampling
Are there any alternatives to CVS?
An amniocentesis is a procedure that involves using a needle to remove some of the amniotic fluid that surrounds your baby in your uterus (womb). However, an amniocentesis can only be performed from 15 weeks.
It is possible to have a detailed scan or a blood test but these tests can only show if your baby may have a problem.
What does the procedure involve?
Removing the tissue usually takes less than ten minutes. There are two ways to perform CVS.
- Transabdominal sampling - Your obstetrician will inject local anaesthetic into the skin and then place a thin, hollow needle through your abdominal wall and into the placenta (see figure 1).
- Transcervical sampling - Your obstetrician will place a thin tube into your vagina, across the cervix and into the placenta.
What complications can happen?
- Discomfort or cramping
- Failed culture
- Uncertain results of your baby’s chromosome pattern
- Infection in the womb
- Premature rupture of your membranes
- Vaginal spotting or bleeding
How soon will I recover?
Your baby’s heartbeat will be monitored for a while using the ultrasound scan and then you will be able to go home.
You should rest for the next couple of days.
Most results of CVS are normal.
If the results show that there is a problem, your obstetrician will discuss the options with you.
CVS is usually a safe and effective way to help find out if there is a problem with your pregnancy.
Author: Mr Andrew Woods MBBS MRCOG FRANZCOG
Illustrations: Hannah Ravenscroft RM
This document is intended for information purposes only and should not replace advice that your relevant health professional would give you.