Endoscopic ultrasound

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Endoscopic ultrasound is a medical procedure in which an endoscopically directed ultrasound is used to image thoracic and abdominal viscera.

A probe is inserted into the esophagus, stomach and duodenum via esophagogastroduodenoscopy. Among other uses, it allows for screening for pancreatic cancer, esophageal cancer, and gastric cancer as well as benign tumors of the upper gastrointestinal tract. It also allows for biopsing of any focal lesions found in the upper gastrointestinal tract. This is done by inserting a needle through the stomach lining into the target.

Endoscopic ultrasound is performed with the patient sedated. The endoscope is passed through the mouth and advanced to through the esophagus to the suspicious area. From various positions between the esophagus and duodenum organs within and outside the gastrointestinal tract can be imaged to see if they are abnormal and they can be biopsied by a process called "fine needle aspiration." Organs such as the liver, pancreas and adrenal glands are easily biopsied as are any abnormal lymph nodes. In addition the gastrointestinal wall itself can be imaged to see if it is abnormaly thick suggesting inflammation or malignancy. The quality of the image produced is directly proportional to the frequency used. Therefore a high frequency produces a better image. However, high frequency ultrasound does not penetrate as well as lower frequency ultrasound so that the examination of the nearby organs is not possible. The procedure is performed by gastroenterologists who have had extensive advanced training.

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