What Is Endoscopic Ultrasound?

What to expect when undergoing an EUS test

Table of Contents
View All
Table of Contents

Endoscopic ultrasound (EUS) is a test that uses a camera and sound waves to produce live images of parts of the digestive system. This includes organs such as the stomach, pancreas, and gallbladder, as well as nearby structures and tissues like lymph nodes.

To perform an EUS, a healthcare practitioner will sedate you and insert a flexible tube called an endoscope in and through your mouth or anus. Once the tube reaches the area that needs to be evaluated, it can be viewed on a computer screen and checked for abnormalities. Sometimes a biopsy may be taken during the procedure to get a sample or more information.

You are not awake during the procedure and should not feel any pain. Endoscopic ultrasound is a very safe procedure.

Read on to learn why an endoscopic ultrasound may be ordered, how to prepare, and what to expect before, during, and after this test.

what to expect during endoscopic ultrasound
Verywell/Emily Roberts

Endoscopic Ultrasound Indications

Endoscopic ultrasound is helpful for seeing parts of the digestive system. It may be ordered to confirm or rule out a suspected digestive disease or a condition.

An EUS will give more detailed information than an X-ray or an external ultrasound.

A healthcare provider may want to do an endoscopic ultrasound when there is a need to:

  • Investigate a possible cause for abdominal pain or weight loss
  • Evaluate pancreatic conditions such as pancreatitis
  • Assess any nodules in the lining of the digestive system
  • Investigate abnormalities in the digestive system and other organs, such as tumors
  • Analyze and stage cancer of the esophagus, stomach, rectum, or pancreas

Endoscopic Ultrasound Prep

It is necessary to prepare for endoscopic ultrasound. Your provider will give you instructions that will include:

  • Fasting: When done for the upper digestive tract, you have to fast for about six hours before the procedure begins.
  • Colon cleansing: If an EUS is done on the lower digestive tract, you will need to "clean out" your colon by fasting, taking laxatives, or using enemas.
  • Adjusting medications: Tell your medical team about all the medications you currently take. You may need to stop certain medications, like blood thinners, for a period of time before the test. If you're fasting and still need to take medication, you may be allowed to swallow it with a small sip of water.

Because the procedure involves sedation, you may need to take a day off to have the test done.

Endoscopic Ultrasound Procedure

Endoscopic ultrasound is usually done in a hospital. The duration of the test varies greatly but usually lasts about one hour.

Before the Test

You will be asked to change into a hospital gown and lie on a hospital bed. Nurses and other staff members will take a health history by asking several questions and will provide any forms that need to be signed.

An IV will be started to give fluids and to give the sedatives that will make the procedure more comfortable. 

During the Test

You will be wheeled into the room where the test takes place. For a lower digestive tract test, you will be asked to lay on you left side.

There will be an anesthesiologist and nurses who may attach various monitors in order to monitor vital signs during the test.

Some sedation will be given through your IV and you will fall asleep.

The endoscope will then be passed down through the mouth or threaded through the anus to gain access to the digestive tract.

Ultrasonic waves are then emitted to create images of the digestive tract, which are transmitted onto the computer screen.

If needed, samples (biopsies) can be collected.


You will wake up in recovery and be monitored for about an hour to ensure that all has gone as expected.

Let the staff know if you have any symptoms like unusual pain or nausea. Ginger ale or water may be given during this recovery time. It may be longer before food is allowed.

After your vital signs are stable and it’s clear that there is no concern for any complications, you will be given instructions on going back to normal activity and how/when to take any medications. You will then be sent home with a friend or relative

Risks and Complications

Serious complications after having an endoscopic ultrasound are rare.

You may have a sore throat for a few days after the procedure if the endoscope is inserted into the mouth and down the throat. The medical team can recommend how to treat this at home and long it will last.

If a biopsy was done, there may be bleeding at the site where the sample was taken, but it should stop on its own.

Serious but rare complications of an EUS include:

  • Having a reaction to the sedatives used during the procedure
  • Infection
  • Aspirating (breathing in) stomach contents

With any endoscopic test, there is a risk of creating a hole in the digestive tract (called a perforation). If this happens, surgery will be necessary to repair the hole. However, this is rare.

Mention any unusual symptoms that occur after an EUS to your healthcare team, especially pain, vomiting, fever, or bleeding.

EUS Results

Some information about how the test went and initial results may be given directly to you in recovery.

More detailed information and the results of any biopsies that were taken will be available later, usually in about a week.

A follow-up visit with your healthcare provider may be scheduled to go over the results of the test and any next steps that are needed.

A Word From Verywell

Endoscopic ultrasound can give so much information about what is happening in the digestive tract. It’s considered to be very safe and it is done under sedation in order to have patients be as comfortable as possible.

It may feel stressful to be told that such a test is needed and then undergo it. Talk with your healthcare provider about your worry and stress because they can adjust the procedures to diminish some of the difficulty. Ask questions about the test and how and when results will be available to lessen your anxiety. 

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  • Hamada T, Yasunaga H, Nakai Y, et al. "Severe bleeding and perforation are rare complications of endoscopic ultrasound-guided fine needle aspiration for pancreatic masses: an analysis of 3,090 patients from 212 hospitals.” Gut Liver. 2014 Mar;8(2):215-8. DOI: 10.5009/gnl.2014.8.2.215.

  • Lakhtakia S. "Complications of diagnostic and therapeutic Endoscopic Ultrasound.” Best Pract Res Clin Gastroenterol. 2016 Oct;30(5):807-823. DOI: 10.1016/j.bpg.2016.10.008.

By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.