An exam using ultrasound (sonography) is a procedure that uses absolutely no radiation and therefore can be used during pregnancy. The principle of sonography is based on the use of ultrasonic waves in the imperceptible range, and can be used on all soft tissues.

The examining physician sees two-dimensional live images that provide information about the size, shape, and structure of the examined area on a monitor. The ultrasound examination requires an experienced diagnostician, because the quality of the exam results depend heavily on the examining physician.