Diagnostic Ultrasound Scan

An ultrasound scan is a way of looking at soft tissues within the body, using sound waves rather than radiation and so it is thought to be safer than other imaging methods.

What is ultrasound?

The sound waves used are at an extremely high frequency and so they cannot be heard. The waves are passed into the tissues and travels through soft tissues. When they hit something more bense (such as bone), the waves are reflected back. The strenth and frequency of the waves being 'echoed' back determines the density of the underlying tissue.

The sound waves are transmitted into an image which is shown on a computer screen. This is different to therapeutic ultrasound where no image is produced and the main aim of the procedure is for therapy purposes.

What happens during an ultrasound scan?

There are not normally any special instructions to be followed before an ultrasound scan, unless it is of the abdomen or pelvis, in which case you may be asked not to eat for 8-12 hours, or to ensure you have a full bladder for your appointment.

An ultrasound transmission gel is applied to the area being scanned to ensure good contact. A wand or probe (usually with a circular head) is then moved over the area, through which the sound waves are emitted. The sound waves are bounced back through the wand, down the wire and transmitted on the computer monitor.

The picture displayed is continually changing so images of the valves of heart opening and closing can be seen. Dynamic ultrasound (where the body part is moved during the scan) is particularly useful in some cases, for example shoulder impingement syndromes.

What are they used for?

Ultrasound scans are used to look at soft tissues, to determine their size, shape, consistency and any abnormalities. They are particularly useful for tendon injuries, especially tendinopathy (tendonitis) of the Achilles tendon and Patella tendons. And of course they are used to look at unborn babies.