Ultrasonography is an imaging technique used very often in the medical field for purposes of diagnosis or evaluation. It is a completely noninvasive procedure that involves the use of high-frequency sound waves to map an image of internal body structures. The type of sound used, often called ultrasound, is at frequencies of two to 18 megahertz, far above the range which the human ear can detect.
Ultrasound waves are transmitted through a hand-held probe known as a transducer, which also detects the way that the sound waves interact with the object being viewed. This data is translated into a visual image on a screen. These images are not usually very clear to the untrained eye, so a trained medical professional called a sonographer must interpret the image. The exact frequency emitted by the transducer is precisely controlled and will depend on the part of the body that is being imaged.
The most well-known use of ultrasonography is in obstetrics, in which it is used to view an unborn fetus. Fetal ultrasonography serves a variety of purposes. The placement of the placenta, the relative position of the baby, as well as its gender and the health of its major organs, can all be determined through ultrasonography. Potential complications and multiple births can also be detected, making ultrasonography a valuable tool during the course of prenatal care. Barring any prior complications, it is typical for a routine fetal ultrasound to be performed when the fetus has reached a gestational age of 20 weeks.
There are also many other applications of ultrasonography outside of obstetrics. Most areas of the body can be viewed through the use of ultrasound. The heart, bones, kidneys, digestive tract, muscles, and nerves are just some of the organs and systems which can be observed with ultrasonography. One of the only organs that cannot be observed well by this technique is the lungs, because they contain air, which keeps the ultrasound waves from passing through them.
The value of ultrasound as such is not limited just to diagnostics, but has some therapeutic applications as well. For example, ultrasound can be used to clean teeth and to treat cataracts. Focused in a certain way, it can also be used to destroy kidney stones and treat cancerous growths. Ultrasonography has only been in wide use since the latter part of the 20th century. Given the relative newness of this type of medical technology, further discoveries are likely to be made in relation to its usefulness for diagnosis as well as treatment.