Endoscopic ultrasound is an endoscopy procedure used for the purpose of evaluating internal organs of the chest and abdomen, along with the lining of the gastrointestinal tract. The flexible echoendoscope is passed through the mouth into the stomach and small intestine. It provides a more detailed information about the viscera compared to the conventional abdominal ultrasound and is used for various diagnostic and staging purposes. It can also be used to localize a site for biopsy or to drain a lesion. via https://www.cincinnatichildrens.org