What is an ultrasound scan?

An ultrasound scan uses sound waves to make real-time pictures of the inside of the body.

Ultrasound is a painless and generally non-invasive test. Ultrasound does not use radiation.

During an ultrasound scan, a handheld transducer (probe) sends sound waves into the part of the body being checked. The reflected sound waves (echoes) return to the device and are turned into an image on a screen.

Types of ultrasound scans

Common types of ultrasound scans include:

• abdominal ultrasound — looks at the internal organs of the abdomen, such as the liver, gallbladder, pancreas and spleen
• obstetric/pregnancy ultrasound
• female pelvis ultrasound or transvaginal ultrasound
• breast ultrasound
• renal ultrasound — scans the urinary tract, including the kidneys and bladder
• transrectal ultrasound

Other types of ultrasounds include:

• Doppler ultrasound echocardiogram, which shows how blood flows through the heart
• 3D ultrasound, which shows a 3-dimensional picture of the inside of the body
• 4D ultrasound, which creates a 3-dimensional picture in motion

When is an ultrasound scan used?

Ultrasounds may be used for screening, diagnosing many conditions or to help with treatment.

Ultrasound scans can be used to:

• look at organs, such as the heart, thyroid, breast, prostate and liver
• check muscles, tendons and ligaments for nerve problems and muscle tears
• assess lumps to see if they are fluid-filled cysts or solid lumps
• monitor blood flow, find blood clots, aneurysms (bulging arteries), narrowing of arteries and decreased blood flow
• help guide procedures such as injections or biopsy (a small tissue sample taken for testing)
• screen for breast cancer or assess breast lumps

In pregnancy, ultrasounds check how far along the pregnancy is (gestational age), monitor growth and look for complications. These are usually offered at 11 to 14 weeks and 18 to 22 weeks — known as the first and second trimester scans. Extra scans are usually only done if needed. Some people choose to do ultrasound scans, including 3D and 4D scans, for non-medical reasons. You should discuss having these scans, or if an ultrasound is needed, with your obstetrician or GP.

Is an ultrasound safe?

Yes. Ultrasound is very safe. It does not involve radiation and is safe to use during pregnancy.

Where can I get an ultrasound?

You can have an ultrasound at:

• private radiology or imaging clinics
• hospitals
• some specialist clinics

You will usually need a referral from your doctor or a health professional.

What happens during an ultrasound?

During most ultrasound scans, you will be asked to lie on your back or side. Gel is placed on the skin to help the sound waves travel. It is performed by a specially trained doctor, radiologist or sonographer (ultrasound technician).

They will move the transducer on the gel, over the area being checked. You may feel gentle pressure, but it shouldn't cause discomfort. Let them know if you feel any pain or if anything is concerning you.

An ultrasound scan usually takes around 20 minutes.

Transvaginal ultrasound

A transvaginal ultrasound looks at the female pelvis, uterus, cervix, fallopian tubes and ovaries, through the vagina.

If you are having a transvaginal ultrasound scan, follow the instructions from your doctor.

You will be asked to empty your bladder and undress from the waist down, with a gown or sheet to cover you. The transducer (probe) is slightly larger than a tampon. It is covered in a protective sleeve, lubricated with gel and gently inserted into the vagina.

You can request a female sonographer to perform a transvaginal ultrasound, if you wish.

If you don't want to have a transvaginal ultrasound, or your sonographer doesn't consider it suitable (such as in children), you may be offered a pelvic ultrasound instead.

Transrectal ultrasound

Transrectal ultrasounds look at the prostate gland. A narrow transducer (probe), coated in gel, is inserted into the rectum. This can be uncomfortable but shouldn't be painful.

How do I prepare for an ultrasound scan?

Tips to prepare for an ultrasound scan:

• Bring your referral letter and any previous ultrasound scan or x-ray to be used for comparison and assessment.
• Follow the instructions provided to you. You may need to fast or drink plenty of water and not go to the toilet before the procedure.
• Leave your jewellery and valuables at home.
• Wear clothing that will make it easy to access the area being scanned.

If you have diabetes, tell the ultrasound staff before your ultrasound. If you have any questions or concerns, contact the imaging practice for advice.

Are there any side effects or complications of an ultrasound?

Ultrasounds do not involve radiation and are considered very safe. They are used routinely in pregnancy.

Internal ultrasounds may cause mild, short-term discomfort.

Ultrasound can't see through bone or soft dense tissue, such as scarring or calcification (calcium build-up in tissue). It does not work well for areas that are full of air, such as the lungs. Ultrasound images may be less clear for people living with overweight or obesity, because the sound waves bounce back early, before reaching the organ being checked.

Are there alternatives to an ultrasound scan?

Yes, other imaging tests that may be used include:

• computed tomography (CT) scan
• magnetic resonance imaging (MRI) scan
• x-ray

Your doctor will recommend what is best for your situation.

Resources and support

For more information about how and why ultrasounds are performed, see the Inside Radiology website.

For information on how ultrasound is used in cancer diagnosis and treatment, visit the Cancer Council.

Read more on sonography at NSW Health.

Call healthdirect on 1800 022 222 at any time to speak to a registered nurse (known as NURSE-ON-CALL in Victoria) for more information and advice.