An Introduction to EUS (Endoscopic Ultrasound)

Disclaimer: This is a professional nursing blog related to Endoscopy and the target audience is any Registered Nurse. The benefit of using this blog is that it is an easy way to learn about topics in nursing you may not know about. It’s easy to read and user friendly, with several interesting links to videos and more in depth articles from reliable sources.

Purpose: The purpose of this post is to 1) introduce RNs to a relatively new technology in gastroenterology called Endoscopic Ultrasound, 2) Educate RNs about when and why EUS is used, 3) Inform RNs what to expect when their patients undergo EUS procedures and 4) Share information with RNs that they can use to inform patients about EUS procedures.

Evaluation: At the end of this post, please click on the Survey Monkey link to evaluate the information presented, rate this blog or simply leave a comment.

Alright, so you have a patient who has been scheduled for an EUS. What the heck is that, you say? What are you supposed to tell your patient when she asks you questions about the procedure? What should you and your patient expect afterward? When should you expect test results? Well, hopefully after you read this entire post you will have all the information you need to answer all of these questions for yourself and your patient.

What is EUS?

EUS stands for Endoscopic Ultrasound. This technology has been around since the late 1980’s, but was only offered at major research and teaching hospitals until very recently(“Endoscopic Ultrasound”, 2010). Now, more endoscopy fellowship programs began offering EUS training, so more local hospitals are beginning to offer this service line, although there are still relatively few endoscopists performing EUS.

To begin, the term endoscopy in this post refers to an examination of the digestive tract by inserting a flexible, fiberoptic camera either via the mouth or the rectum. In EUS, the endoscope also has an ultrasound transducer tip on it. With this specialized scope, not only can the doctor visualize the lining of the digestive tract endoscopically, but using high-frequency sound waves, can also produce highly detailed images of the musculature and surrounding structures and organs. Therefore the MD is looking at two images simultaneously on a split screen or two monitors side by side(“Endoscopic Ultrasound”, 2010).

An “upper EUS” refers to an esophagogastroduodenoscopy with ultrasound. In this test, the doctor can visualize the esophagus, mediastinum, stomach, duodenum, pancreas, liver, gallbladder, spleen, adrenal glands, parts of the kidneys and all surrounding lymph nodes.  A “lower or rectal EUS” usually refers to a flexible sigmoidoscopy with ultrasound, though in certain instances, the sigmoidoscopy is not performed. In this test, the doctor can view the muscle walls of the anal sphincters, the anus, rectum, sigmoid colon, bladder, prostate and surrounding lymph nodes(“Endoscopic Ultrasound”, 2010) .

EUS processor – image copyright of Hitachi Corporation

There are two basic type of EUS scopes: linear and radial.  Each scope gives a different view for the endoscopist, but both have Doppler capability, to differentiate blood vessels from other ductal structures, and to tell the difference between arteries and veins.  The linear scope gives a 90′ wedge-shaped image. Echo-tipped flexible needles can be passed through the scope to perform ultrasound-guided fine needle aspirations and core biopsies. The image using a linear scope looks like this:

Linear EUS scope and ultrasound image produced - image copyright of Pentax of America, Inc.

Follow this link to view a short video illustrating the use of a linear scope and FNA:

A radial scope is used to obtain a 360′ image and this is the picture the doctor sees:

EUS radial scope and ultrasound image produced – image copyright of Pentax of America, Inc.

Follow this link to see a great video showing the use of a radial EUS scope in rectal cancer staging:


Why not just get a CT scan or a conventional ultrasound?

Standard ultras0und of the abdomen and mediastinum is limited due to intervening air. And, while CT scans are good for getting a general overview of the body, EUS gives more detailed imaging without the patient being exposed to radiation (DiMaio, 2011).

Okay, so why and when is EUS used?

EUS is used to further investigate lesions, masses, and cysts that have been found during a routine endoscopy, conventional ultrasound, CT scan or MRI. EUS can provide detailed ultrasound images and measurements of tumors. By using a flexible needle through the scope to perform fine-needle aspiration (FNA), EUS can also give real-time tissue diagnosis of many different cancers, thus preventing the need for more invasive surgical biopsies. It is also helpful in N and M cancer staging, in that any lymph nodes involved can be visualized, counted and measured (N-staging) and EUS imaging can visulize whether the cancer has spread beyond the muscle walls (M-staging).  The images and information obtained during EUS procedures, frequently presented at tumor board meetings, assist surgeons, oncologists and radiation oncologists in designing treatment for patients (“Understanding EUS”, 2011).

This technology can also be used to evaluate fecal incontinence by imaging and measuring musculature at the internal and external anal sphincters.  For patients with intractable pain from chronic pancreatitis or pancreatic cancer, EUS can be used to perform a celiac plexus nerve block or complete neurolysis. And for patients with esophageal and duodenal cancers, EUS can be used to perform EMR (endoscopic mucosal resection) to completely remove the cancerous lesion without having to undergo major surgery (“Understanding EUS, 2011).

Indications for use:


  • Lung cancer
  • Esophageal cancer
  • Gastric cancer
  • Pancreatic cancer and cystic neoplasms
  • Bile duct cancer
  • Rectal cancer


  • Submucosal mass (GIST -gastrointestinal interstromal tumor, carcinoids, etc…)
  • Endoscopic mucosal resection
  • Choledocholithiasis (Gallstones in the bile duct)
  • Chronic abdominal pain
  • Unexplained acute pancreatitis
  • Fecal incontinence
  • Abnormal imaging (thickened gastric wall, unexplained bile duct dilation)
  • Therapeutic EUS (celiac plexus block/neurolysis)

(“Endoscopic Ultrasound”, 2010)Nursing Considerations:

As with most endoscopic procedures, patients will receive either conscious sedation analgesia or general anesthesia and must have patent intravenous access. Patients will be placed in a left lateral decubitus or left modified Sims position for the procedure.  Also, the patient should be NPO for a minimum of 6 – 8 hours prior to the procedure.   Dentures and/or partials can be removed just prior to start time.

For upper EUS procedures, a plastic bite block will be placed in the patient’s mouth to protect the scope from the teeth and vice versa.  An anesthetic spray, such as Cetacaine or Exactacaine, is sprayed in the back of the throat to reduce gagging. Therefore, to reduce risk of aspiration, the patient should remain NPO for 1-2 hours post-procedure, or until the gag reflex returns. Patients may feel bloated and have a sore throat after an upper EUS (Wilson, 2009).

For a rectal or lower EUS, the MD may order the patient to have 1-2 Fleets enemas the morning of the procedure. A full colon prep is usually not warranted, as only the rectum and/or sigmoid colon will be examined (Wilson, 2009).

Obtaining Procedural Consent:

This  procedure can be done on the upper GI tract or the lower GI tract. When it’s an upper EUS, it is part of an EGD – lower, part of a flexible sigmoidoscopy and if the doctor “sees” anything that needs to be investigated by a pathologist (i.e., lymph node, cyst, mass) he will want to perform a fine needle aspiration at that time. The MD should explain all risks with the patient – only slightly more risk than a normal endscopy if a needle is used for FNA – and include perforation of the esophagus and/or bowel wall, bleeding and pancreatitis (Adler, et al., 2005) .   So, your consent for procedure should read: Esophagogastroduodenoscopy with endoscopic ultrasound and possible fine needle aspiration.  For a rectal or lower EUS, the consent should be worded:  Flexible sigmoidoscopy with endoscopic ultrasound and possible fine needle aspiration (Wilson, 2009).

Additional information for Nurses and Patients:

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Adler, D. G., Jacobson, B. C., Davila, R. E., Leighton, J. A., & Quereshi, W. A. (2005). ASGE guideline:

complications of EUS. Gastrointestinal Endoscopy, 61(3), 502. Retrieved from

DiMaio, C. J. (February 4, 2011). Endoscopic ultrasound (EUS). Retrieved from

Endoscopic ultrasound. (2010). Retrieved from

Endoscopic ultrasound (EUS)/FNA (fine needle aspiration). (2010). Retrieved from

Understanding EUS (endoscopic ultrasonography). (2011). Retrieved from

Wilson, J. A. (2009). EUS (endoscopic ultrasound). Departmental inservice.

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Filed under Endoscopy Nursing, Gastroenterology Nursing, Nursing, Ultrasound

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