Ultrasound: What to Expect and How to Prepare

A small hand-held device called a transducer sends high-frequency sound waves into the body and listens for the echoes that bounce back from different tissues. A computer turns those echoes into an image on a screen, updating continuously — which is why an ultrasound can show movement, such as blood flowing or a baby shifting position.

Clear gel is put on the skin first. Sound does not travel through air, and the gel removes the thin layer of it between the transducer and you. It is water-based, wipes off, and is often warmed.

• pregnancy, including the scans usually offered in the first and second trimesters
• organs in the abdomen, such as the liver, gallbladder, kidneys and pancreas
• the pelvis, including the uterus and ovaries, or the prostate
• muscles, tendons, ligaments and joints
• blood vessels — how well blood is flowing, and whether there is a clot
• the thyroid, breast tissue, and lumps close to the surface of the body
• guiding a needle accurately during an injection, a biopsy or drainage of fluid

Ultrasound is safe, portable and quick, and it images movement, which makes it a common first choice. It has real limits too: sound waves do not pass through bone or air, so ultrasound is not used to look inside the skull in adults or at the lungs, and images can be less clear the deeper the structure being examined. Which test answers a particular question is a clinical decision — ask the doctor who referred you if you are unsure why this one was chosen.

Getting the preparation wrong is the most common reason an ultrasound has to be rebooked. There is no single rule, because the preparation exists to make one particular area visible. Some common examples of the shape it takes:

• Abdominal scans usually require a period of fasting, so that food and gas do not obscure the organs and the gallbladder is easier to see.
• Scans of the pelvis or kidneys from the outside often require a full bladder, which means drinking a set amount of water at a set time beforehand and not going to the toilet.
• An internal pelvic scan is usually done with an empty bladder — the opposite instruction, which is exactly why the clinic tells you which applies.
• Scans of muscles, joints, the thyroid or soft-tissue lumps generally need no preparation at all.

Wear a two-piece outfit where you can, so only the area being scanned has to be uncovered. Allow a little extra time if you are told to arrive with a full bladder — it is uncomfortable to sit with, and clinics know that.

None of these is unusual to raise, and staff are used to arranging around them. Asking when you book gives the clinic the chance to allow more time or to roster the right person, which is rarely possible on the day.

• your referral, if it has not already been sent to the clinic
• your Medicare card, and any concession or DVA card
• private health insurance details, if the scan is being done as a private patient in hospital
• any previous imaging or reports for the same problem, if they were done elsewhere
• a support person, if you would like one with you

1. You check in at reception and hand over your referral, along with your Medicare card and any concession card.
2. The sonographer collects you and asks about your symptoms — this shapes what they look at, so it is worth answering fully.
3. They explain the examination and answer questions before anything starts.
4. You undress only as far as the area being scanned requires, and are covered with a gown or sheet.

The room is usually dimmed so the screen is easier to read. The sonographer slides and rotates the transducer over the area, sometimes pressing a little more firmly to see past gas or to reach a deeper structure. They will stop at intervals to record still images and measurements — the quiet is concentration, not a finding.

You may be asked to change position, to breathe in and hold, or to roll onto your side. If anything is uncomfortable, say so; pressure can usually be adjusted.

A radiologist may come in during or after the examination to scan a particular area themselves or to ask you about your symptoms. This is a normal part of how many practices work and is not a sign that something has been found.

The time depends on how much detail is needed and how many structures are being examined. Scans of blood vessels tend to take the longest, because each segment is examined and measured in turn.

Ask the clinic how long your examination usually takes when you book, and allow extra for check-in and changing.

Most people find an ultrasound easy. Where an area is already tender — an injured tendon, an inflamed gallbladder — the pressure needed to get a clear image can be briefly uncomfortable. Sonographers expect to be told, and can adjust.

Occasionally people notice mild tenderness in the area afterwards. It usually settles within a few hours.

There is no X-ray exposure of any kind, and no known harmful effect from the sound waves at the levels used in a clinical setting. That is a large part of why ultrasound is used so heavily in pregnancy and in children, and why an examination can be repeated when a doctor needs to follow something over time.

Very occasionally an ultrasound contrast agent is injected into a vein to look at particular structures more clearly. That is uncommon, it is not the same substance used in CT or MRI, and it would be explained to you beforehand.

Sonographers are highly skilled at acquiring and recognising what they see, but interpreting the examination and issuing the report is the radiologist’s role. A sonographer declining to tell you what they can see is not a sign of bad news — it is how the reporting works.

Ask the clinic when the report is expected to be sent, then book a follow-up appointment with your referring doctor to go through what it means for you.

There are no after-effects and no restrictions. You can eat, drive and return to work immediately, and if you fasted for the examination you can eat as soon as it is over.

If you had an injection or a biopsy done under ultrasound guidance, that is a different procedure with its own aftercare, and the clinic will give you specific instructions. Contact your doctor if you feel unwell afterwards. In an emergency, call 000.

In Australia, medical imaging is arranged through a referral (also called a request) from a doctor. You take that referral to an imaging provider, and for most types of imaging you may choose which provider you go to, unless your referral names one.

Whether a Medicare benefit applies to a particular examination, and how much of the fee it covers, depends on the item and on your circumstances. Some providers bulk bill some examinations; others charge a fee, and you pay the difference between that fee and any Medicare benefit.

• Ask the imaging provider what the examination will cost you before you book, and whether they bulk bill it.
• Ask whether an internal scan, or a second area, is charged separately.
• Services Australia publishes current information on Medicare and bulk billing, and MBS Online publishes the Medicare Benefits Schedule itself. Both are linked in the sources below.