Advanced Ultrasound Endoscopy

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 Colonoscopy and Flexible Sigmoidoscopy 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.

How Traditional Ultrasound Differs From EUS

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 lower digestive tract, one can obtain high-quality ultrasound images of the organs inside the body.

Advantages of Placing the Transducer on the Endoscope

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 can also obtain information about the layers of the intestinal wall, as well as adjacent areas such as lymph nodes and the blood vessels.

Additional Applications: Doppler and Fine Needle Aspiration (FNA)

Other uses of EUS include studying the flow of blood inside blood vessels using Doppler ultrasound and obtaining 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).

WEAR’s Health Watch segment on Endoscopic Ultrasound