Amniocentesis test

Amniocentesis is a prenatal diagnostic test done after 15 weeks of pregnancy to confirm if your baby has a genetic disorder or a difference with their chromosomes. Your doctor may recommend this test in some cases, but having this test is a choice. Your maternity care provider can discuss the benefits and risks in your situation. Amniocentesis can help you make important decisions about your pregnancy.

During this test, a specialist doctor inserts a needle through your belly into your uterus to take a sample of amniotic fluid. The fluid is examined in a laboratory to check your baby's chromosomes (genes).

Your doctor may recommend amniocentesis if your baby is at a high chance of having a genetic condition, for example, if:

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

The decision to have or not to have an amniocentesis is yours. While your healthcare team can explain why they recommend a test in your situation, they will respect your personal choice.

Read about congenital disorders.

If there's a chance your baby has a genetic problem, amniocentesis can help you make an informed decision about continuing your pregnancy. It can also help you prepare for what is to come, if your child has a genetic condition and you choose to continue the pregnancy.

Before you have the test, it's a good idea to think about why you are choosing to do it, and how you might feel once you get the results. You might like to discuss your options with your partner, a friend or family member, or a healthcare professional such as your doctor or midwife.

Your doctor may also refer you to a genetic counsellor to help you make a decision.

Before the procedure, your doctor must explain what they will do and the risks of the procedure, as part of shared decision making. It is your choice whether to have the test or not, and you must give informed consent before you go ahead.

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 a specialist doctor with training will perform an amniocentesis.

You can get an amniocentesis in some hospitals and specialist ultrasound clinics.

Medicare will usually cover part of the cost of the procedure, but depending where you go, other costs may be involved. For example, if you have a private obstetrician, there may be consultation fees for the procedure. Ask your doctor about the costs involved in your specific circumstances.

Right before the procedure, your doctor will do an ultrasound and check your baby and placenta. The ultrasound can help them decide where to insert the needle.

After cleaning the skin over your abdomen, your doctor will then insert a very fine needle into your uterus (womb) through your abdomen. About 20 to 30mL of fluid is removed through the needle. The needle is then removed. The actual test only takes a few minutes.

Throughout the process, your doctor will use ultrasound to guide the needle. This way, they will reduce the risk of the needle touching your baby.

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 the procedure, your baby's heart rate will be checked.

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

It is your right to have someone with you during the test, if you want to.

Depending on your circumstance and the tests requested by the doctor, your results may be available within 3 to 5 working days or 1 to 2 weeks. Ask your doctor when you can expect to receive your results.

After having amniocentesis, you may feel some mild uterine cramping. You may also have minimal 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 very small amount that stops by itself within a week and replenishes
• your waters breaking
• infection of your membranes and uterus (chorioamnionitis)
• injury to your baby
• miscarriage

There are a range of tests that can check whether your baby has a genetic or chromosomal problem.

Chorionic villus sampling (CVS) is another diagnostic test which is done between 11 and 14 weeks of pregnancy. During CVS, your doctor takes a small sample of your placenta to check your baby's genes. Talk to your doctor about whether it is appropriate for you, and the risks and benefits of the test compared to amniocentesis.

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

If you are worried about the risks of an amniocentesis or CVS, you may choose to do screening tests only.

If you receive an abnormal result from your screening tests, you may choose 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.

COPE the Centre of Perinatal Excellence 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.

Other languages

The COPE (Centre of Perinatal Excellence) website offers valuable information during pregnancy and early parenthood and can be translated into many community languages.

Aboriginal and/or Torres Strait Islander peoples

You can find out more about Aboriginal and/or Torres Strait Islander pregnancy health on Stronger Bubba Born, or watch the How to Have a Safer Pregnancy video.

The Australian Nurse-Family Partnership Program (ANFPP) is a nurse-led home visiting program that supports Aboriginal and/or Torres Strait Islander people who are pregnant.