Endoscopic Ultrasound (EUS) allows a doctor to obtain images and information about the digestive tract and the surrounding tissue and organs. Ultrasound testing uses sound waves to make a picture of internal organs. During the procedure, a small ultrasound device is installed on the tip of an endoscope. An endoscope is a small, lighted, flexible tube with a camera attached. By inserting the endoscope and camera into the upper or the lower digestive tract, the doctor is able to obtain high-quality ultrasound images of organs.