An ultrasound test uses high-frequency sound waves to create images of internal organs or tissues. It works by sending low-energy sound waves against tissue. Some waves pass through and others bounce back. As sound waves bounce back, they are recorded and displayed on a computer screen or television-type monitor.

The image created by an ultrasound is considered to be less clear than those from CT scans (computed axial tomography) or MRIs (magnetic resonance imaging). However, ultrasound is often used for a wide array of procedures because it is fast, generally noninvasive, less expensive and more specific for some conditions than a CT scan or MRI.

Ultrasound can be used to examine numerous internal structures. Within these structures, it may help to detect many abnormalities and diagnose conditions. It is more useful in detecting structural abnormalities (such as shapes or masses that appear suspicious) than abnormalities that tend to occur throughout the body (e.g., inflammation of several organs).

In addition to its diagnostic role, ultrasound may be used as therapy. Ultrasound may be used in physical therapy and occupational therapy at higher frequencies because the thermal effects have been found to help treat musculoskeletal injuries, break down scar tissue and stretch and warm tendons.

Preparations for an ultrasound test depend on the type of ultrasound being performed. However, most ultrasound tests require little or no preparation. Most often, ultrasounds are performed on an outpatient basis, but these tests are also used in hospitals as part of diagnostic patient care.

There is no pain associated with an ultrasound test. Test results are evaluated by a radiologist and then relayed to the patient’s primary healthcare provider. If the ultrasound shows a problem, additional diagnostic tests, such as an MRI, may be recommended.

In extensive studies, no risks associated with properly conducted medical diagnostic ultrasound have been documented. On the other hand, ultrasound therapy can pose some risks, such as burns from misuse. However, such problems are uncommon when the therapy is performed by a properly trained healthcare professional.