Chorionic villus sampling (CVS)

Chorionic villus sampling (CVS) is a diagnostic test (Opens in new tab) sometimes done during pregnancy. It is used to find out if your baby has a genetic disorder (Opens in new tab) or chromosomal disorder, such as Down syndrome. 

During a CVS test, your doctor takes a sample of cells from your placenta. 

CVS is not part of routine antenatal care and is not offered to everyone during pregnancy.

CVS can help you make informed decisions about continuing your pregnancy. If your doctor recommends this test, it is important to know that choosing a CVS is your decision. You may make decisions based on your personal, cultural or family values.

CVS is usually done during your first trimester, between 11 weeks and 13 weeks and 6 days.

Why might I be offered CVS?

Your doctor may recommend CVS if you:

• have had a prenatal screening test result that suggests your baby may have a higher chance of a genetic condition
• have a child with a genetic or chromosomal condition
• will be over 35 years of age when your baby is due
• or your partner are carriers of a genetic condition
• have a family member with a genetic condition
• want certainty about a diagnosis of Down syndrome or another genetic or chromosomal condition

Ask your doctor to explain why they are offering CVS.

You may feel anxious or stressed if your doctor recommends a CVS test, especially if this follows a screening test that showed a higher chance of a genetic condition. These feelings are common. 

Your healthcare team can support you along your journey. You may also find it helpful to speak with someone you trust or ask your doctor for a referral to a genetic counsellor. 

Some people find that doing a diagnostic test early in pregnancy can reduce their anxiety. It can give you time to understand your results and what they mean for you. This can help you make an informed decision about your pregnancy. 

Read more about mental wellbeing during pregnancy. 

Read more about questions to ask your doctor about tests and scans. 

CVS tests are usually done at a hospital by a specially trained doctor.

Before your CVS, your doctor will check your baby and the location of your placenta. They will clean your abdomen (tummy) and then begin your CVS test.

Your doctor will insert a very thin needle into your placenta. This can be done through your tummy (known as an abdominal tap) or through your cervix (known as transcervical). The needle takes a very small sample of cells from your placenta.

The CVS test is done under the guidance of an ultrasound. Your doctor may apply a local anaesthetic to numb the skin before the CVS needle is inserted. The ultrasound helps the doctor to move the needle and avoid contact with your baby.

Your sample will be sent to a laboratory to be examined. 

After your CVS, your doctor will:

• check your baby’s heart rate
• check your amniotic fluid levels 
• check the site where they inserted the needle
• offer you an anti-D injection if your blood type is Rh-negative 

Your healthcare professionals will help explain your results and all your options.

Your doctor will only do a CVS if you have given written informed consent. 

Some people feel pain during a CVS test. Many people find the procedure to be less painful than they thought. 

You may also feel cramping or period-like pain (Opens in new tab) during your test. 

CVS can cause some complications, including:

• vaginal bleeding
• infection
• your waters breaking
• miscarriage

There is a small risk of miscarriage with every pregnancy. Having a CVS can slightly increase that risk.

It is also possible that there is a technical issue with your test. You may need to repeat your CVS, or your doctor may recommend an amniocentesis.

If you choose not to have a CVS test, you can consider other options, including:

• diagnostic tests — amniocentesis or genetic testing after your baby is born
• screening tests — non-invasive prenatal test (NIPT), combined first trimester screening or second trimester maternal serum screening

Screening tests cannot diagnose a medical condition. They can only tell you if your baby has a higher chance of having some genetic conditions.   

As part of shared decision making, you can discuss these options with your doctor. This can help you make an informed decision about which test is right for you.  

Read about understanding informed consent and your rights when having a baby.  

Read more about routine antenatal tests.

Read more about checkups, scans and tests during pregnancy. 

The Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG) has a fact sheet about chorionic villus sampling (CVS) (Opens in new tab).

Perinatal Anxiety & Depression Australia (PANDA) (Opens in new tab) offers mental health support for parents and families during pregnancy and in their first year of parenthood.  

The Royal Women’s Hospital has helpful information about your pregnancy care options (Opens in new tab). 

Languages other than English

The Australian Government, Department of Health, Disability and Ageing has translated pregnancy resources (Opens in new tab) into many community languages. 

Information for Aboriginal and/or Torres Strait Islander peoples

You can find out more about Aboriginal and/or Torres Strait Islander pregnancy health at Stronger Bubba Born (Opens in new tab) or watch the How to Have a Safer Pregnancy (Opens in new tab) video.

Baby Coming You Ready (Opens in new tab) offers support for Aboriginal and/or Torres Strait Islander parents to be and new parents.

The Koori Maternity Service (KMS) (Opens in new tab) program provides access to holistic, culturally safe maternity care for Aboriginal and/or Torres Strait Islander peoples.

Information for sexually and gender-diverse families

The Gidget Foundation (Opens in new tab) offers pregnancy support for all LGBTQIA+ families.