Endoscopic Ultrasound (EUS or endosonography)
Endoscopic Ultrasound is a procedure in which an endoscope (a thin, tube-like instrument used to look at tissues inside the body) or a rigid probe is inserted into the body through the rectum.
The endoscope or probe has a light and a lens for viewing. A device at the end is used to bounce high-energy sound waves (ultrasound) off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram.