Endoscopic ultrasound is a test that allows your doctor to look at the walls of your esophagus, stomach, and upper gastrointestinal tract. This test may also be used to look at the airways and lungs. The test does not use X-rays or other radiation.

The doctor uses a thin, lighted tube that bends. It's called an endoscope, or scope. The scope has an ultrasound probe and camera at the tip. The doctor gently inserts the scope into your mouth, down the esophagus, and into the stomach to the area to be examined. The scope can take pictures of organs to look for problems in the esophagus, stomach, liver, gallbladder, pancreas, and the first part of your small intestine, called the duodenum.

If EUS is being used to look at the airways and lungs, the scope is moved down the throat and through the windpipe into the airways to the lungs (bronchi). Or the scope can be put down the esophagus if the doctor wants to get pictures of the lymph nodes close to the bronchi.

EUS may also be used to guide a biopsy of the lung, lymph nodes, or other areas.