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What is ultrasonography?
In ultrasonography (also called ultrasound), high-frequency sound waves,
inaudible to the human ear, are transmitted through body tissues. These sound
waves are reflected back to a receiver by the tissues, and the echoes vary
according to the tissue density. The echoes are recorded and translated into
video or photographic images that are displayed on a monitor.
An ultrasound may be performed over the skin (transcutaneous), or an
endoscope (small ultrasound probe) may be inserted into and placed within an
organ such as the stomach or colon (endosonography).
Ultrasound images help in the diagnosis of a wide range of diseases and
conditions. The idea for ultrasonography came from sonar technology, which makes
use of sound waves to detect underwater objects.
Ultrasound is used to create images of soft tissue structures, such as the
intestinal tract, gallbladder, liver, heart, kidneys, pancreas, bladder, thyroid
glands, prostate, rectum and sphincter muscles, female reproductive organs, and
even of babies in the uterus. Ultrasound can also measure the flow of blood
in the arteries to detect blockages.
Ultrasound may be used to detect the following:
- Fluid-filled structures called cysts, or solid growths, or abnormal
growths in the liver, spleen, or pancreas that may be present in a variety of
organs
- Abnormal enlargement of the spleen size or density of an organ
- Cancer of the liver
- The depth of invasion of a gastrointestinal cancer
- Abnormal lymph nodes
- Gallstones
- Anal sphincter damage (the anal sphincter is the muscle that controls bowel
movements)
- Abnormal blood vessels called varices
Ultrasound cannot be used to view bones because they are too dense for the
sound waves to penetrate.
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