What is an ultrasound scan

Ultrasound uses high frequency waves to produce pictures of the inside of your body. It is most useful for examining soft tissues, and as a real time procedure ultrasound can show movement, blood flow and structure.

What to expect

Before your Ultrasound

Some preparation may be required, but we go over everything with you prior to the examination so you know exactly what you need to do to be ready for your scan.

You may be asked to:

  • Not drink or eat for four to eight hours before your appointment - though water, black tea or black coffee (with no milk or sugar) may be allowed. Please let us know if you are a diabetic as you may prefer an earlier appointment
  • Attend the examination with a full bladder
  • Continue to take all prescribed medications as usual
  • Wear comfortable clothing, with two-piece outfits being preferred
  • Not carry out any preparation at all (i.e. carry out your normal activities)

Arriving for your Ultrasound

Please arrive at least 10 minutes before your scheduled appointment time, and bring your referral form from your doctor or health professional. This allows us to explain the procedure and for you to fill out a consent form if this is required.

You are welcome to bring a support person to the appointment if you like.

You may be asked to change into a gown in a private area before the area is scanned.

Then you will be brought to the ultrasound room and asked to lie down on the examination bed. 

During your Ultrasound

Specially trained sonographers, or radiologists, perform your ultrasound.

A water-based gel is applied to the skin surrounding the area to be examined. This gel helps us obtain a clearer image.

The sonographer or radiologist moves the hand-held device called a transducer which emits the ultrasound waves, and receives the resulting echoes. The transducer is slowly moved around your skin, recording images of the tissue being examined from different angles. Occasionally the transducer may need to be firmly pushed in an area on your body; which may be uncomfortable for a short period of time. Your sonographer will tell you beforehand if they are going to do this.

Depending on what part of your body is being scanned, an ultrasound commonly takes about 30 minutes but you should allow about an hour from your arrival to departure.

An ultrasound-guided injection takes 15-30 minutes, but can take longer if multiple injections are required. The transducer helps a doctor find the right spot to place the needle and either give the injection, or obtain a biopsy sample if that is needed. We numb the injection area beforehand, so even if multiple biopsies are needed to obtain a clear result, it is probable you will feel pressure rather than pain during the procedure.

After your Ultrasound

Generally, after your scan you can resume normal activities. This includes eating, drinking, working and exercise.

Your ultrasound scan report based on a radiologist interpretation is sent to your doctor as soon as possible. In discussion with your physician the findings and next steps in your diagnosis and treatment can then take place.

Often for a guided injection or biopsy we recommend you bring a driver, particularly if you believe you might feel faint. Alternatively you may need to wait for a short time after the procedure until you feel more comfortable.

If you would like a copy of your Ultrasound images, please talk to a member of our Reception team before you leave. 

You are in good hands

Ultrasounds are a safe, painless and fast way to take images of your body.

Frequently Asked Questions

What is Ultrasound used for?

Ultrasound is particularly useful in visualising abdominal structures and organs, and can also be used to guide the needle in certain kinds of injection therapies.

Other ultrasound uses include:

  • Foetal ultrasounds to assess the health of the foetus during pregnancy
  • Bone sonometry, to determine bone fragility
  • Ultrasound guided biopsies
  • Assessment of gallbladder
  • Determining the health of an infant brain, spine, heart and hips
  • Ophthalmic ultrasound to visualise ocular structures
  • Breast ultrasounds to help assess breast tissue health
  • Doppler ultrasound to listen to the foetal heartbeat
  • Doppler ultrasound to assess blood flow and other internal structures and organs
  • Echocardiogram to view the heart and blood flow
  • Examination of internal organs such as the bladder, spleen, liver, thyroid, pancreas, kidneys and other structures.

The technology can help diagnose issues such as blocked or narrowed blood vessels, reduced blood flow to organs, infections, tumours and cysts, congestive heart failure, damage due to heart attack, heart valve issues.

Ultrasound - science explanation

Ultrasound relies on producing, detecting and interpreting sound echoes to build an internal picture

Human hearing operates in the frequency range of 20 hertz to 20,000 hertz (20kHz).

Ultrasound applies to all acoustic energy above these frequencies. Diagnostic sonographic scanners typically operate at a level hundreds of times greater than human limits between 2 to 18 megahertz.

Ultrasound-based diagnostic imaging techniques visualise subcutaneous body structures such as tendons, muscles, joints, vessels and internal organs.

Its reflection technology (echo) registers the pulse reflected at the boundary of two tissues with different acoustic resistance. A sound wave is produced by a piezoelectric transducer encased in a probe, where strong, short electrical pulses from the ultrasound machine make the transducer ring at the desired frequency.

The sound is focused through the transducer shape, a lens in front of the transducer, or a complex set of control pulses from the ultrasound scanner machine itself.

This focusing produces an arc-shaped sound wave from the transducer face which travels into the body and focuses at a desired depth. Human tissues are non-homogeneous responding to ultrasonic waves, and their passage through organs, muscles, fat, skins and other body parts leads to refraction, reflection, scattering and absorption of energy.

An image is created based on how long it took for the signal to be reflected back - and much like bats flying in the dark, the soundwaves create a fluid digital image of the underlying body structures. This is achieved through the probe picking up the reflected waves and a computer working out the relative distances of tissues from these waves, and create a picture.

With two probes it is possible to create three-dimensional images, and to measure fluid flow, including for example, blood.

Ultrasound is very good at showing muscle and soft tissue, and clearly showing solid and fluid-filled spaces. Ultrasound doesn’t work well through bone however, so it is not used to look at the brain.

Book an Ultrasound today

You will need a referral from your GP or Specialist for this service. 

Please call us on 04 978 8600 if you have any questions.

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