2d ultrasound is the traditional and original method of viewing a baby’s organs and skeletal features. Simply put, this method is what has been commonly used to view the prenatal progress. Today’s advanced technology with 3d ultrasound allows the viewing of the surface images of your baby, and with great detail. These images, known as sonograms, are produced with the same frequency sound waves used in the traditional 2d ultrasound. These sonogram images are also produced in 4d ultrasound, a process that allows you to view your baby in motion, also known as real-time.