What is an ultrasound scan?

An ultrasound is a very safe procedure that uses soundwaves to create images of your baby while you are pregnant. No needles or radiation are used.

How does ultrasound work?

During a pregnancy ultrasound:

• The sonographer (person doing the ultrasound) puts gel on your abdomen (belly).
• A handheld wand called a transducer is placed on your skin and gently moved around.
• Pulses of sound waves go from the transducer to your baby in your uterus (womb).
• The soundwaves create echoes that go back to the ultrasound machine.
• A computer converts the soundwave echoes into pictures.

What is a transvaginal ultrasound scan?

In some situations, you might need a transvaginal ultrasound to get clear images of your baby. This is more likely early in your pregnancy when your baby is still very small.

Why should I have an ultrasound scan?

When are ultrasound scans offered during pregnancy?

Several ultrasound scans are routinely recommended and offered during pregnancy. It is your decision to go ahead and have each ultrasound scan.

Dating scan

If needed, a dating scan is usually done in the first trimester. It can be done any time during pregnancy.

This ultrasound is used to estimate your baby’s due date. It can also:

• confirm if you are pregnant with one baby or multiple babies
• check that your pregnancy is not ectopic (baby growing outside the uterus)

Nuchal translucency scan

The nuchal translucency scan (also called an NT scan) is done after 11 weeks and before 14 weeks of pregnancy.

The term ‘nuchal translucency’ refers to one of the key measurements taken during this ultrasound. This measurement will help your doctor to assess your baby’s chance of having a chromosomal condition, such as Down syndrome.

Similar to a dating ultrasound, this scan can also check your baby’s growth, estimate your due date and check the physical development of your baby.

Morphology scan

A morphology scan is an ultrasound scan usually done between 18 and 22 weeks of pregnancy.

This ultrasound can check the structure and growth of your baby’s body organs. Measurements made at the morphology scan help estimate your baby’s gestational age and size.

This scan can also check your baby’s heart rate and rhythm. The sonographer can make sure your placenta is in a good position and measure the length of your cervix.

At the morphology scan, you can usually find out the sex of your baby. You will be asked if you want to know.

Why else might I need an ultrasound during pregnancy?

In some cases, your doctor or midwife might recommend extra ultrasounds. You might need an extra scan if you:

• have pregnancy complications
• are worried about your baby's movements

Who performs an ultrasound scan during pregnancy?

A nuchal translucency scan is usually performed by a specially-trained technician called a sonographer.

Some medical specialists, such as obstetricians, have had specialised training and can carry out ultrasound scans. Some midwives also perform certain ultrasounds.

You might have your ultrasound in a clinic, an imaging centre or in a hospital.

Can an ultrasound scan harm my baby?

Ultrasound is a safe and pain-free test. There is no increased risk of miscarriage or harm to your baby.

The sound waves used are at very low frequency and so will not hurt you or your baby. Unlike an x-ray, there is no radiation used.

Do I have to have ultrasound scans?

Your doctor or midwife is likely to recommend you have one or more ultrasound scans during your pregnancy. This is so they can check how your baby is developing.

Talk to your doctor or midwife about antenatal tests and ultrasound scans to understand why they are offered. You and your doctor and midwife can decide together which tests you will have.

You will be given information about each test so that you can make an informed decision. It’s your choice whether to have each scan.

What are the alternatives to ultrasound scans?

Your doctor or midwife can monitor your baby’s heartbeat and growth at your regular check-ups.

You could have a different blood test to find out if your baby is likely to have a genetic condition. This test is called non-invasive prenatal testing (NIPT). It can identify about 99% of babies with Down syndrome. NIPT also screens for other conditions. It is done after 10 weeks of pregnancy. You need to pay a fee to have this test.

Questions for your doctor

Here are some questions you might want to ask your midwife or doctor:

• Why are you recommending this ultrasound?
• What are the benefits of having this ultrasound?
• Are there risks if I choose not to have the ultrasound?
• What does the ultrasound involve?
• When will I get the results?

More questions to ask your doctor about tests and scans.

ASK YOUR DOCTOR — Preparing for an appointment? Use the Question Builder for general tips on what to ask your GP or specialist.

How do I prepare for an ultrasound scan?

Before you have an ultrasound scan, it’s a good idea to think about why you are choosing to do it, and what you might learn. As well as seeing the first exciting images of your baby, you might find out that something is not going to plan. Talk it over with your partner, a friend or family member.

Your doctor, midwife or the ultrasound clinic, will tell you how to best prepare for your scan. In many cases you won’t need to do anything special to get ready.

You may be asked to:

• wear loose clothing
• drink water beforehand so that there is fluid in your bladder

Check what you need to do to prepare when you book your appointment.

If you are having a nuchal translucency scan, you will also need a blood test.

How much does an ultrasound cost?

Medicare will cover some of your ultrasound scan costs. Ask your midwife or doctor if you should expect any out-of-pocket costs for your specific situation.

You may have to pay out-of-pocket costs depending on where you go for the test. Ask about this when you book your appointment.

When will I get the results of my ultrasound scan?

An ultrasound scan usually takes around 30 minutes. The results are often available on the same day, but it can take longer.

You can ask for copies of your baby’s ultrasound images to take home.

A copy of the full report will be sent to your doctor.

You should discuss the results with your doctor. If there are any concerns, they can explain what the findings mean and any next steps.

What do the ultrasound scan results mean?

Having ultrasound scans can provide you and your doctor or midwife with information about your pregnancy and the development of your baby.

While these scans can reassure you that your baby is developing normally, you may also learn that your baby has an abnormality.

If the results of your ultrasound bring up any health concerns, you can talk to your doctor or midwife about further testing. You might be referred for diagnostic tests, such as:

• chorionic villus sampling
• amniocentesis

You can also visit to a genetic counsellor to talk through what your test results mean.

Resources and support

Your doctor, obstetrician or midwife can answer your questions and give you more information about having an ultrasound scan during pregnancy.

Visit Inside Radiology to learn more about ultrasound scans and other imaging tests.

Western Sydney local health district website and the Royal Women’s Hospital in Melbourne provide information about pregnancy in many languages.