What is Endoscopic Ultrasound?
Endoscopic Ultrasound (EUS) combines endoscopy
and ultrasound in order to obtain images and information
about the digestive tract and the surrounding tissue and
organs. Endoscopy refers to the procedure of inserting a
long flexible tube via the mouth or the rectum to visualize
the digestive tract (for further information, please visit the
articles), whereas ultrasound uses high-frequency sound waves to
produce images of the organs and
structures inside the body such as ovaries, uterus, liver,
gallbladder, pancreas, aorta, etc.
Traditional ultrasound sends sound waves to the organ(s)
and back with a transducer placed on the skin overlying the
organ(s) of interest. images obtained by traditional
ultrasound are not always of high quality. In EUS a
small ultrasound transducer is installed on the tip of the
endoscope. By inserting the endoscope into the upper or the
lower digestive tract one can obtain high quality
ultrasound images of the organs inside the body.
Placing the transducer on the tip of an endoscope allows
the transducer to get close to the organs inside the body.
Because of the proximity of the EUS transducer to
the organ(s) of interest, the images obtained are
frequently more accurate and more detailed than the ones
obtained by traditional ultrasound. The EUS also
can obtain information about the layers of the intestinal
wall as well as adjacent areas such as lymph nodes and the
Other uses of EUS include studying the flow of
blood inside blood vessels using Doppler ultrasound, and to
obtain tissue samples by passing a special needle, under
ultrasound guidance, into enlarged lymph nodes or
suspicious tumors. The tissue or cells obtained by the
needle can be examined by a pathologist under a microscope.
The process of obtaining tissue with a thin needle is
called fine needle aspiration (FNA).