Endoscopic ultrasound (en-doh-SKAH-pik uhl-truh-sound) (EUS) enables the physician to image and biopsy various abnormalities within or adjacent to the GI tract. Masses or cysts seen on a prior CT scan or endoscopy within the wall of the GI tract (esophagus, stomach, small intestine, colon) or outside the GI tract (pancreas, gallbladder, lymph nodes, adrenal glands) are often further evaluated by EUS. Using the ultrasound for guidance, masses and cysts can be biopsied with a thin needle. For lesions already known to be cancer in the esophagus, stomach, small intestine, and rectum, EUS allows the physician to accurately stage the tumor. A tumor’s stage refers to the degree to which its has grown.

EUS can be performed through the upper GI tract or the colon. The special endoscope used for EUS has a small ultrasound probe on its tip. For the procedure, you will typically lie on your left side. A sedative will be given throughout the exam to prevent any pain or discomfort. The physician will then guide the scope to the area of interest and turn on the ultrasound. When necessary, the thin needle is passed down the endoscope to take biopsies.

Possible complications of EUS include pancreatitis (inflammation of the pancreas), infection, bleeding, and perforation. These complication are very uncommon.

EUS takes 30 minutes to 90 minutes. After the procedure, you will need to stay at the hospital for 1 to 2 hours until the sedative wears off. The physician will make sure you do not have signs of complications before you leave.


For EUS of the upper GI tract, the stomach and duodenum must be empty for the procedure to be accurate and safe. You will not be able to eat or drink anything after midnight the night before the procedure. For EUS of the colon or rectum, a colonoscopy prep (see separate page) is necessary. You must also arrange for someone to take you home—you will not be allowed to drive because of the sedatives. The physician may give you other special instructions.