Ultrasound (also called sonography) is a diagnostic medical procedure that uses high-frequency sound waves to produce dynamic visual images of organs, tissues or blood flow inside the body. The high-frequency sound waves are transmitted to the area of interest and the returning echoes recorded. This type of procedure is often referred to as a sonogram or ultrasound scan.

First developed in World War II to locate submerged objects, the technique is now widely used in virtually every branch of medicine.

Sonography can be used to examine many parts of the body, such as the abdomen, breasts, female reproductive system, prostate, heart and blood vessels and more.

In obstetrics ultrasound is used to study the age, number, and location of the fetus, as well as to examine the fetus for birth defects or other potential problems. In the abdomen, it is used to detect abnormalities such as gallstones or liver disease. Heart disease can be identified through cardiac ultrasound. Ultrasound can also be used for therapeutic purposes such as muscle/joint heating and lithotripsy.

Sonography is increasingly being used in the detection and treatment of heart disease, heart attacks and vascular disease that can lead to stroke. It is also used to guide fine-needle tissue biopsy to assist in taking a sample of cells from an organ for lab testing (for example, a test for cancer in breast tissue).
Diagnostic ultrasound is noninvasive, involves no radiation, and avoids the possible hazards—such as bleeding, infection, or reactions to chemicals—of other diagnostic methods.

The technologists who perform these procedures are known as sonographers and vascular technologists (sonographers specializing in imaging and tests of blood vessels)