Sonography uses a device called a transducer to send out ultrasound waves and listen for the echo. A computer translates the ultrasound waves into an image. A trained technician can see, measure, and identify structures in the image. A specially trained physician then reads the images to help diagnose medical conditions.

A sonogram image can show the sizes and shapes of structures, good and bad, inside the body. The harder and denser the tissue (bone would be the hardest and densest) the more it bounces sound waves back to the transducer and the brighter the resulting image becomes.