Endoscopic ultrasonography, usually called EUS, pairs a flexible endoscope with a miniature ultrasound probe at its tip. While a standard endoscope shows the surface lining of the digestive tract, the ultrasound adds a view beneath that surface: through the layers of the wall and into neighboring organs such as the pancreas, bile ducts, gallbladder, liver, and nearby lymph nodes.
Because it shows areas that ordinary endoscopy and many scans cannot capture in fine detail, EUS often answers questions that other tests leave open.
Why it is recommended
Your gastroenterologist may suggest EUS to take a closer look at something found on a CT scan or other imaging, to evaluate cysts or masses in the pancreas, to search for stones in the bile duct, or to examine a lump beneath the lining of the esophagus, stomach, or rectum.
EUS also helps show how deep an abnormality goes, which guides treatment planning. When a tissue sample is needed, the doctor can pass a very fine needle through the scope, guided by the ultrasound image, often avoiding a more invasive procedure.
How to prepare
For an upper EUS your stomach must be empty, so you will not eat or drink for several hours beforehand. If the rectum is the area being examined, you may be asked to use an enema or a light prep. Review your medicines with your care team, especially blood thinners, since a needle sample may be taken, and arrange a ride home.
During the procedure
You will receive sedation through an IV, and most patients remember little or nothing of the exam. The endoscope is passed gently through the mouth, or the rectum, depending on the area being studied, while your doctor watches the ultrasound images. Any needle sampling happens while you are sedated, so you will not feel it. Most exams are finished within an hour.
Afterward
After a short recovery you can usually go home the same day, perhaps with a mild sore throat or some bloating that settles on its own. Do not drive for the rest of the day.
Your doctor will go over the initial images with you; results from any tissue samples take several days. Your care team will explain the findings and what, if anything, comes next.
Questions about your care?
This page is general education, not personal medical advice. Your care team is happy to talk through what it means for you.
Preparing for a procedure? See preparation instructions