COMMON DIAGNOSTIC TESTS

ULTRASOUND (sonography; sono is the Latin root word for sound)

Unlike other diagnostic tests which use x-rays, an ultrasound, also called a sonogram, operates by using sound waves with a frequency that is too high to be audible. An ultrasound is very safe and painless to the patient. This type of diagnostic test may sound familiar as it is routinely used in checking the growth of a fetus during a woman's pregnancy.


How an ultrasound works
The testing process begins when a liquid medium, a gel or oil, is spread onto the patient's skin where the area of study lies underneath. For example, a woman who is having an ultrasound to check the growth of her fetus will have the liquid spread directly onto the skin of her abdominal area. The liquid medium optimizes the transmission and pick-up of soundwaves by eliminating air between the transducer and skin. A transducer is a small device, shaped much like a microphone, that emits soundwaves and receives returning soundwaves or echoes. The gel or oil is harmless, although some patients may find that the liquid is quite cold when it is spread on their skin.

Once the liquid has been spread, the transducer is then placed onto the lubricated area. The transducer emits sound waves into the area of focus. When the sound waves encounter a border between two tissues that conduct sound differently, echoes will bounce back to the transducer. The echoes are read as data by a computer and then transformed into images that appear on a small monitor. As the transducer moves along the body, the images will correspond with the changing placement.


What an ultrasound looks at
An ultrasound is capable of producing images of the following areas:

Did you know…?
The basic operating system of an ultrasound is similar to that of sonar tracking which was first used by submarines during World War I.