Ultrasonography is a type of medical imaging that uses high-frequency sound (ultrasound) waves to produce images of internal organs and other tissues.

During an ultrasound, a device called a transducer converts electrical current into sound waves, which are sent into the body’s tissues. Sound waves bounce off structures in the body and are reflected back to the transducer, which converts the waves into electrical signals. A computer converts the pattern of electrical signals into an image, which is displayed on a monitor and recorded as a digital computer image. No x-rays are used, so there is no radiation exposure during ultrasonography. 

Procedure for Ultrasonography

If certain parts of the abdomen are being examined during an ultrasound, people may be asked to refrain from eating and drinking for several hours before the test. Normal gas build up in the intestines from eating or drinking can sometimes make ultrasound images difficult to obtain. In other instances, such as an ultrasound of female reproductive organs, women may be asked to drink a large amount of fluid to fill their bladder.

Usually, the examiner places thick gel on the skin over the area to be examined to ensure good sound transmission. A handheld transducer is placed on the skin and moved over the area to be evaluated.  Uses of Ultrasonography

Ultrasound images are acquired rapidly enough to show the motion of organs and structures in the body in real time (as in a movie). For example, the motion of the beating heart can be seen, even in a fetus.

Ultrasonography is effectively used to check for growths and foreign objects that are close to the body’s surface, such as those in the thyroid gland, breasts, testes, and limbs, as well as some lymph nodes.

Ultrasonography is effectively used to image internal organs in the abdomen, pelvis, and chest. However, because sound waves are blocked by gas (for example, in the lungs or intestine) and by bone, ultrasonography of internal organs requires special skills. People who have been specifically trained to do ultrasound examinations are called sonographers.

Ultrasonography is commonly used to evaluate the following:

Heart: For example, to detect abnormalities in the way the heart beats, structural abnormalities such as defective heart valves, and abnormal enlargement of the heart’s chambers or walls (ultrasonography of the heart is called echocardiography)

Blood vessels: For example, to detect dilated and narrowed blood vessels

Gallbladder and biliary tract: For example, to detect gallstones and blockages in the bile ducts

Liver, spleen, and pancreas: For example, to detect tumors and other disorders

Urinary tract: For example, to distinguish benign cysts from solid masses (which may be cancer) in the kidneys or to detect blockages such as stones or other structural abnormalities in the kidneys, ureters, or bladder

Female reproductive organs: For example, to detect tumors and inflammation in the ovaries, fallopian tubes, or uterus

Pregnancy: For example, to evaluate the growth and development of the fetus and to detect abnormalities of the placenta (such as a misplaced placenta, called placenta previa)

Musculoskeletal structures: For example, to detect swelling within a joint or a torn ligament

Ultrasonography can also be used to guide doctors when they remove a sample of tissue for a biopsy. Ultrasonography can show the position of the biopsy instrument, as well as the area to be biopsied (such as a mass). Thus, doctors can see where to insert the instrument and can guide it directly to its target.