Endoscopic Ultrasound (EUS)


Endoscopic ultrasound (EUS) is a minimally invasive procedure used to assess digestive and lung diseases. EUS can be performed through the upper GI tract or the colon. This nonsurgical procedure uses high-frequency sound waves to produce detailed images of the lining and walls of the upper and lower digestive tract and nearby organs such as the pancreas, liver and gallbladder.

EUS is often used to further evaluate cysts or masses seen on a prior CT scan or endoscopy. 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 assess the stage of the tumor.


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 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.

What To Expect

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. A small ultrasound transducer is installed on the tip of an endoscope (a small, lighted, flexible tube with a camera attached). The physician will then guide the endoscope to the area of interest and turn on the ultrasound. 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. Because the EUS transducer can get close to the organ(s) being examined, the images obtained with EUS are often more accurate and detailed than images provided by traditional ultrasound. When necessary, the thin needle is passed down the endoscope to take biopsies.

What Happens Afterwards?

EUS takes 30 minutes to 90 minutes. After the procedure, you will need to stay at the facility for 1 to 2 hours until the sedative wears off. Since the effects of the sedative may take up to 24 hours to subside, some fatigue is common after the examination. You should plan to go directly home and relax for the rest of the day.

Reprinted and modified from The National Digestive Diseases Information Clearinghouse