Ultrasound imaging (or sonar) uses high-frequency sound waves to produce images of the body. Sound waves are beamed into the body causing return echoes that are recorded to visualise structures beneath the skin.
The studies are generally non-invasive and provide images for initial assessment of most conditions affecting the body. Ultrasound is also used to guide minimally invasive procedures – such as drainage of pleural or abdominal fluid – as well as fine needle aspiration or biopsies.
WHAT DOES THE PROCEDURE ENTAIL?
A specialised transducer is used to project the sound waves, and to receive the return signals. A contact gel is applied onto the patient’s skin so that the sound waves are not affected by air as they pass through the skin.
HOW SHOULD I PREPARE FOR MY ULTRASOUND?
Ultrasound studies of the upper abdomen require patients to avoid eating and drinking with the exception of water for six to eight hours prior to the examination.
For ultrasound studies of the kidneys, bladder and other pelvic organs (uterus, ovaries and prostate), it is recommended that patients drink at least four to six glasses of water approximately one to two hours prior to the examination for the purpose of filling the bladder. The extra fluid in the bladder moves air-filled bowel loops away from the examined organs, so that they are more visible during the ultrasound test.