Pancreas Endoscopic Ultrasound (EUS)
Christopher J. DiMaio, MD
Assistant Attending Phyisican
Gastroenterology & Nutrition Service
Memorial Sloan-Kettering Cancer Center
What is an Endoscopic Ultrasound (EUS)?
For many patients who have, or who are suspected of having pancreatic 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. 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:
- Pancreatic masses and tumors
- Pancreatic cysts
- Chronic pancreatitis
- Autoimmune pancreatitis
- Acute pancreatitis
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
These findings listed above can be caused by both benign and malignant conditions. Thus, it is important that you discuss the reason for the EUS with your physician.
Can biopsies of the pancreas be taken at the time of my EUS?
One of the advantages of performing an EUS is that pancreatic biopsies can be obtained at the time of the examination. These biopsies, often referred to as FNA, or fine-needle aspiration, can allow for your physician to collect tissue samples which can later be analyzed under a microscope. Special needles, designed to be used with the EUS scope, allow the physician to insert a small needle through the wall of the stomach or intestine directly into the pancreas. Because this is done at the time of the EUS, the physician is able to direct the needle to the exact location of interest all while watching the needle with the EUS.
FNA is most commonly performed to evaluate masses or tumors of the pancreas, in order to determine if cancer is present. Another very common reason for performing an FNA is in the evaluation of pancreatic cysts. In these cases, the needle is used to sample the fluid which is contained in the cyst. This fluid can be sent for biochemical, cytologic, and molecular analysis in order to help characterize the type of pancreatic cyst you have.
In certain circumstances, larger biopsy samples of the pancreas may be required. EUS allows the physician to obtain “core biopsies” of the pancreas in a similar fashion to FNA.
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, which results in very detailed imaging of the organ. The endoscopist can often times visualize details of the pancreas 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, unlike with CT or MRCP, pancreatic biopsies can be safely and easily obtained at the time of the exam.
Are there any risks of having an EUS?
Because sedation, or in some cases, general anesthesia is used during EUS, there is a risk for cardiac and/or pulmonary complications during an EUS procedure.
As with any endoscopic procedure, there is a small risk of causing bleeding or a tear of the GI tract (called a perforation). These complications can often be managed endoscopically, however emergency surgery may be required in the worst case scenario. Fortunately, the risk of a severe complication like this from EUS is very low, less than 1% of the time in most cases.
Biopsies/FNA of the pancreas can also result in bleeding, infection, or acute inflammation of the pancreas (called acute pancreatitis). FNA of pancreatic cysts can result in infection of the cyst. This has been reported to occur in 1-2% of cases. Your physician may give you an antibiotic during the procedure to prevent infection, and may prescribe a short course of oral antibiotics after the procedure.
How should I prepare for my EUS?
You should not have anything to eat or drink for approximately 8 hours before your EUS. Typically, patients are asked to refrain from eating or drinking after midnight the night before their test.
Your physician may ask you to hold any blood thinning medications for one week before your test. Examples include aspirin, Plavix, and coumadin. You may be allowed to take your other medications on the morning of your test. It is extremely important that you tell your physician what medications you are on, and discuss if any need to be stopped before the test.
If you have a history of heart or lung disease, you may be required to get a letter from your heart or lung doctors stating that it is safe for you to have an endoscopy and receive sedation.
What should I expect on the day of my EUS?
On the day of your EUS, you will arrive in the endoscopy suite. An IV catheter will be placed in your hand or arm so that you can receive intravenous fluids and sedatives during the procedure.
Once you are brought into the endoscopy room, you will lay down on a bed, usually on your left side (like you are watching TV). In order to monitor your vital signs during the procedure, a blood pressure cuff will be placed on your arm, an oxygen monitor will be placed on your finger, and EKG leads will be placed on your chest. A small nasal cannula will be placed in your nose to give you oxygen during the procedure. A small plastic “bite block” will be placed in your mouth between your teeth, which protects your teeth and prevents any accidental biting of the scope during the procedure.
Sedatives will be injected into your IV before the procedure begins. The procedure usually lasts from 20-45 minutes, but can be shorter or longer. The vast majority of patients do not feel or experience any discomfort during the procedure, as they are usually asleep during the procedure.
When the procedure is finished, you will be brought to a recovery area where you will lay in bed until you are awake. Your vital signs will continue to be monitored during this time. When you are awake, you will be given some juice and a small snack. The recovery period usually lasts between 20 minutes to 1 hour.
Before you are discharged home, you will have an opportunity to meet with your physician to discuss the results of the EUS, and receive further instructions regarding your medications.