Ultrasound is a safe, painless method for examining the internal organs of the body that avoids the use of ionizing radiation. Instead, high-frequency sound waves are generated and the “echoes” that result from their bouncing off the soft tissue structures can be used to measure size, to detect structural abnormalities, to determine whether a lump is solid or fluid filled or to monitor growth of the fetus during pregnancy. Ultrasound images of the heart are called echocardiograms, and the procedure is called echocardiography. Unlike many imaging procedures, ultrasound does not use x-rays, needles or radiation and is painless and non-invasive.

See My Heart | American Society of Echocardiography