What is an Endoscopic Ultrasound (EUS)?

For many patients who have, or who are suspected of having pancreatic OR biliary disease, their doctor may recommend that they undergo a type of procedure called an endoscopic ultrasound, or more often known as EUS.

An EUS is a type of endoscopic examination.  It involves the insertion of a thin tube into the mouth and down into the stomach and the first part of the small intestine. At the tip of the tube is a small ultrasound probe that emits sound waves.  These sound waves bounce off of the surrounding structures, such as the stomach, small intestine, pancreas, bile ducts, and liver.  These sound waves are then recaptured by the probe and converted into black and white images that are then interpreted by your doctor.  Because the pancreas sits next to the stomach and small intestine, EUS allows the physician to get very detailed images of the pancreas.  This procedure is typically performed in an outpatient setting, and usually takes between 20 and 45 minutes.

What are the reasons why I need an EUS?

EUS allows for very detailed imaging and analysis of the  pancreas & bile ducts.  As such, it is an excellent test for evaluating many different kinds of diseases that can occur in the pancreas.  Examples of such pancreatic conditions for which EUS can be extremely useful are:

  • Abdominal pain
  • Pancreatic masses and tumors
  • Pancreatic cysts
  • Chronic pancreatitis
  • Autoimmune pancreatitis
  • Acute pancreatitis
  • Obstructive jaundice
  • Common bile ducts stones

One of the most common reasons that patients are referred for an EUS of the pancreas is to evaluate abnormal findings on a CT (CAT scan), MRI, or ultrasound of the abdomen, or for further investigation of abnormal blood tests such as elevated liver function tests (AST, ALT, bilirubin) or elevated pancreatic enzymes (amylase, lipase).  Patients with certain types of abdominal pain may also be referred for an EUS.  Examples of reasons for referral for an EUS include:

  • Dilated pancreatic duct
  • Dilated bile duct
  • Swollen/inflamed pancreas
  • Suspected stones in the pancreas duct or bile duct
  • Suspected blockage of the pancreas or bile duct
  • History of recurrent episodes of acute pancreatitis

What are the advantages of an EUS, compared to a CT scan, MRI, or ERCP?

There are many different tests which can be used to evaluate the pancreas.  CT scans and MRI are types on non-invasive tests which allow for detailed imaging of the pancreas and the surrounding structures in the abdominal cavity.  CT scans expose the patient to some amount of radiation.  Furthermore, some patients are unable to receive IV contrast for their CT scans (due to allergies or kidney problems), and thus the quality of the pictures will be sub-optimal.  A special kind of MRI called an MRCP can give high-quality pictures of the pancreas, the pancreas duct, and the bile ducts.  However, some patients who are claustrophobic may decide against having an MRI performed.

As discussed, EUS allows the physician to get in very close proximity to the pancreas and bile ducts which results in very detailed imaging of the organ.  The endoscopist can often times visualize details of the pancreas & bile ducts that cannot be seen with either CT or MRCP.  Furthermore, there is no exposure to radiation and no need for contrast to be given.  In addition, because the EUS scope has a video camera on it, endoscopic evaluation of the esophagus, stomach, and first part of the small intestine can also be evaluated at the time of the EUS.  This is important for some patients who are having a work-up for abdominal pain as it allows for a complete examination of the upper GI system.

The biggest advantage of EUS is that pancreatic biopsies can be safely and easily obtained at the time of the exam.