An ultrasound (sometimes called a sonogram) is a noninvasive diagnostic test that uses sound waves to create images of internal organs. The sonographer uses a hand-held device to transmit sound waves through your uterus that echo off your baby. A computer then translates the echoing sounds into video images that reveal your baby’s shape, position, and movements. The series of television-monitor images is called a sonogram. The words ultrasound and sonogram are often used interchangeably. The differences in a 2D and 3D/4D ultrasound are in the sophistication of the equipment and computer software used.
