Ultrasound examination, also called sonography or diagnostic medical sonography, is an imaging method that uses high-frequency sound waves to produce precise images of structures within your body. The images produced through ultrasound examination often provide information that's valuable in diagnosing and treating a variety of diseases and conditions.

Most ultrasound examinations are doing using a sonar device outside of your body, though some ultrasound examinations involve placing a device inside your body.

Despite its valuable uses, ultrasound can't provide images of all areas of your body. But there are several other imaging tests.

Why it’s done:

You may need to undergo an ultrasound for a variety of reasons. Ultrasound may be used, among other things, to:

• Evaluate a fetus
• Diagnose gallbladder disease
• Evaluate flow in blood vessels
• Guide a needle biopsy
• Guide the biopsy and treatment of a tumor
• Check your thyroid gland
• Study your heart
• Diagnose some forms of infection
• Diagnose some forms of cancer
• Reveal abnormalities in the scrotum and prostate

Risks:

Diagnostic ultrasound is a safe procedure that uses low-power sound waves. Although ultrasound is a valuable tool, it does have its limitations. Sound doesn't travel well through air or bone, so ultrasound isn't effective at imaging parts of your body that have gas in them or that are obscured by bone. Rather than using ultrasound to view these areas, your doctor may instead order other imaging tests, such as CT or MRI scans, or X-rays.

How to Prepare:

How you prepare for an ultrasound depends on which area of your body needs evaluation:

• Some ultrasound exams require no preparation.
• Others require that you forego food and liquids for up to 12 hours before the exam.
• Still others require that you not urinate before the exam to ensure that your bladder will be full.