How Does Ultrasound Work?

A transducer emits ultrasound waves and records the echoing waves. When the transducer presses against the skin, it sends small pulses of high-frequency sound waves into the body. The transducer records the sound's pitch and direction changes as it bounces off the internal organs, tissues, and fluids. 

A computer then creates a picture on the monitor in real-time. Ultrasound images are in 2D, 3D or 4D (3D in motion).