diagnostic ultrasonography is the use of ultrasound to visualize hidden body structures. this medical imaging technique is used to display muscles, tendons, and other internal organs. it makes it easier to assess damage done to these structures. obstetric sonography is the name for a number of tests done during the pregnancy of a woman. diagnostic sonography has a wide field of use, including emergency medicine, where it is regularly performed on patients which are in a state of shock or trauma. this test is known as focused assessment with sonography for trauma. it can detect any fluid in the body cavities. doctors can then decide whether life-saving surgery must be performed.