, also called a sonogram, is a diagnostic imaging procedure in which high-frequency sound waves are used to create real-time images of soft tissue, blood vessels, and internal organs of the body. The sound waves are transmitted through a small handheld device called a transducer. During an ultrasound, you will be either seated or lying down, and your doctor will apply a gel to the area that is to be examined, before gently placing the transducer on the area and moving it around. Unlike an x-ray or CT scan, an ultrasound does not use radiation. Its a safe, effective procedure and has no known side effects.