Ultrasound uses sound waves instead of radiation to generate snapshots or moving pictures of structures inside the body. This imaging technique works in a manner similar to radar and sonar. Ultrasound was developed in World War II to detect airplanes, missiles, and submarines that were otherwise invisible.
The doctor or ultrasound technician first coats a small area of your skin with a lubricant to reduce friction. He or she then places an ultrasound transducer, which looks like a microphone, on your skin and may rub it back and forth to get the right view. The transducer sends sound waves into your body and picks up the echoes of the sound waves as they bounce off internal organs and tissue. A computer transforms these echoes into an image that is displayed on a monitor.