An endoscopic ultrasound (EUS) is a test we do to look at the inside the rectum. It's commonly used to look for abnormal tracts in the rectum or for fluid-filled areas. EUS may also be used to help diagnose certain diseases or to drain cysts or abscesses.
EUS shows both ultrasound images and live video of the GI tract. During the test, a flexible tube called an endoscope (or scope) is used. At the end of the scope is a tiny video camera and light. The video camera sends live images to a monitor. The scope also contains a very small ultrasound device. This uses sound waves to create images and send them to a monitor.