Amniocentesis test

Amniocentesis is a prenatal diagnostic test done after 15 weeks of pregnancy to confirm if your baby has a genetic condition or a difference in their chromosomes. 
Amniocentesis can help you make important decisions about your pregnancy.

Your doctor or midwife may recommend this test during your pregnancy. It is your choice to decide if you want an amniocentesis or not. Together with your maternity care provider, you can discuss the benefits and risks in your situation. 

During amniocentesis, your specialist doctor will insert a needle through your abdomen (tummy) into your uterus (womb) to take a sample of amniotic fluid (liquid). The fluid is examined in a laboratory to check your baby’s chromosomes.

Read about routine antenatal tests. 

Read about checkups, scans and tests during pregnancy. 

Your doctor may recommend amniocentesis if your baby has a high chance of having a genetic difference, for example if:

• you had a prenatal screening test and the results suggested your baby has a higher than expected chance of a genetic difference
• you already have a child with a genetic or chromosomal difference
• both parents of the baby are known to be carriers of a genetic condition

Other reasons you may be recommended an amniocentesis include:

• to diagnose a problem with your baby’s neural tube 
• to check for anaemia or lung maturity 
• to identify your baby’s blood type
• if they are worried about infection, for example, cytomegalovirus or toxoplasmosis 

Read about congenital disorders.

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

Here are some questions you might like to ask your midwife or doctor about amniocentesis:

• Why are you offering me this test?
• What are the risks to me and my baby?
• What does the procedure involve?
• Do I need to do anything on the day?
• Who will contact me with the results, and how long will it take?
• Do I need to do anything to care for myself after the procedure?
• How accurate are the results? 

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

Your doctor or midwife will discuss the risks and benefits of amniocentesis with you as part of shared decision making. They may also refer you to a genetic counsellor. A genetic counsellor can help you understand the test, your individual chance of a genetic condition and what the results may mean for you and your baby. 
It is your choice whether to have this test.

Being offered amniocentesis can cause worry or anxiety. It is common to feel concerned about possible test results or about complications from the procedure. 

If there is a chance your baby has a genetic difference, amniocentesis may help you make informed decisions about your pregnancy. It may also help you prepare for the future if your child has a genetic difference and you choose to continue the pregnancy.

You might find it helpful to discuss your worries and options with your partner, a friend or family member, or a healthcare professional such as your doctor or midwife.

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

Amniocentesis is generally safe for both you and your baby, but it does carry a small risk of miscarriage. It's a good idea to discuss the potential benefits and risks of the procedure with your doctor.

Only an obstetrician (a specialist doctor) with specific training will perform an amniocentesis.

Amniocentesis is available at some hospitals and specialist ultrasound clinics.

Medicare usually covers part of the cost of your procedure. Depending on where you have the test, there may be other costs involved. For example, if you see a private obstetrician, you may need to pay consultation fees or procedure fees.

Ask your doctor about the costs involved in your individual circumstances before you book your appointment.

Before the amniocentesis, your doctor will do an ultrasound and check your baby and placenta. This helps them decide where to place the needle.

After cleaning the skin over your abdomen, your doctor inserts a fine needle into your uterus (womb) through your abdomen. They remove about 15 to 30 millilitres of amniotic fluid through the needle and then remove the needle. The procedure usually only takes a few minutes.

Your doctor uses ultrasound throughout the process to guide the needle and reduce the chance of it touching your baby.

If you have a negative blood group, you will be given an anti-D injection.

You can have someone with you during the test, as part of your healthcare rights.

During an amniocentesis, you may feel mild discomfort as your doctor inserts the needle through your skin and uterus. In some cases, you may be offered a local anaesthetic.

After having an amniocentesis, you may feel some mild cramping around your uterus. You may also have some spotting of blood or a few drops of amniotic fluid through your vagina.

In rare cases, amniocentesis can cause complications including:

• leaking of amniotic fluid — usually this is a small amount that stops by itself within a week and builds up again
• your waters breaking
• infection of your membranes and uterus (chorioamnionitis)
• injury to your baby
• miscarriage

There are several tests that check if a baby has a genetic or chromosomal problem.

Chorionic villus sampling (CVS) is one example, and is done between 11 and 13 weeks of pregnancy. During a CVS procedure, your doctor takes a small sample of your placenta to check your baby’s genes. 

You can discuss with your doctor whether this test is right for you. They can explain the risks and benefits of the test compared to amniocentesis.

Screening tests that your healthcare team may discuss with you include non-invasive prenatal testing (NIPT), combined first trimester screening tests and second trimester maternal serum screening tests. These tests cannot diagnose genetic conditions in the way that amniocentesis or CVS can. They can only tell you if your baby is at a higher chance. They are less invasive than amniocentesis or CVS. They involve only a blood test and/or ultrasound.

If you prefer not to have an amniocentesis or CVS because of the risks involved, you may choose to have screening tests instead.

If a screening test shows a higher chance of a genetic difference, you may choose to have amniocentesis or CVS to confirm the result.

Read more about prenatal screening.

The Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG) has a helpful fact sheet about amniocentesis.

Centre of Perinatal Excellence (COPE) is a website and an app that can help you stay informed and feel reassured during pregnancy, birth and the first 12 months of parenthood.

Read about self-care for expecting and new parents at PANDA.

Languages other than English

COPE website offers valuable information during pregnancy and early parenthood and can be translated 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 peoples pregnancy health on Stronger Bubba Born or watch the How to Have a Safer Pregnancy video.