What is Endoscopic Ultrasound (EUS)?

What is Endoscopic Ultrasound (EUS)?

Before we discuss what Endoscopic Ultrasound is, it will be important to review what ultrasound means. Ultrasound is a technique that uses sound waves to create a picture of the inside of the body. In this way an ultrasound is similar to an x-ray, but no radiation is used. It is commonly used to see the fetus during pregnancy to determine the sex of the baby. Endoscopic ultrasound (EUS) is a technique that uses a special endoscope that has an ultrasound machine at the tip. Using the EUS "scope", your doctor can place the ultrasound probe in the gastrointestinal (GI) tract, very close to the area of interest, so that the best possible picture can be obtained. EUS has been shown to be superior to routine x-rays such as abdominal ultrasound, barium studies, CAT scans, and even MRI scans for looking at the local spread of GI cancers, for evaluating lesions in the GI tract that are below the surface, and for evaluating the pancreas and even the bile ducts that drain the liver. This procedure is very highly specialized and is performed by a gastroenterologist who has specialty training in this area.

How is EUS Performed?
To the patient, an EUS is very similar to an endoscopy or "scope" test. EUS can be performed in the upper GI tract or in the lower GI tract. Since you will receive sedation to make the exam painless, you must bring a companion with you to drive you home.

For the Upper GI tract EUS exam, there is very little preparation except fasting after midnight the night before the test. You may drink clear liquids up to six hours prior to your exam, then nothing by mouth (not even water).Your usual medications may be taken with small sips of water. However, if you take blood thinners, aspirin or arthritis medicines such as Motrin, ibuprofen, etc.., you should let your doctor know, as these may need to be stopped before the test. In addition, if you are diabetic, you should also let your doctor know, so that adjustments in your doses can be made for the day of the test. Finally, if you have a history of a heart murmur, rheumatic fever as a child, infection of a heart valve, or an artificial heart valve, you should let your doctor know so that he can determine if antibiotics need to be ordered before the test.


Just before the test, you will receive some medications in your IV that will make you sleepy and very relaxed. Usually, a regular "scope" is first performed in order to see the area of interest. The doctor will carefully guide the scope into your mouth, through your food pipe, past the stomach, and into the first part of the small intestine, called the duodenum. After this scope is removed, the EUS scope is passed down in the same manner. The area of interest is then viewed with the ultrasound probe at the tip of the EUS scope.

For the Lower GI tract EUS exam, you may also be asked to take 2 fleets enemas on the morning of the exam. Your doctor will then guide the EUS scope through the rectum to the area of interest. This test is generally very quick and is done without any medications, similar to a flexible sigmoidoscopy.

What about Biopsies or Sampling Tissue?
Occasionally, EUS reveals a lesion that needs to be sampled. Most of the time, this can be performed during the EUS examination. Your doctor may take a biopsy sample using a forcep or needle. This is generally performed while directly looking at the lesion through the "scope" or occasionally, this can be performed using the endoscopic ultrasound image as a guide.

What are the Risks of EUS?
The risks of EUS are similar to the risks associated with standard endoscopy. While every medical procedure involves some degree of risk, the frequency of complications during endoscopy is extremely low. The major risks are perforation, or creating a hole in the lining of the GI tract, and bleeding. If perforation should occur, it usually requires surgery to repair it. Bleeding may occur at the site of a biopsy or needle sample. Typically minor in nature, bleeding can generally be treated during the endoscopy by injecting medications or cauterizing the bleeding site, but rarely, surgery is required. Fortunately, perforation and bleeding are quite rare. Other minor risks of EUS include drug reactions and complications related to other diseases that you may have. Consequently, you should inform your doctor of all allergic tendencies and medical problems. Occasionally, the site of the sedative injection may become inflamed and tender. This usually is not serious and responds to warm compresses.

After the Test
After outpatient EUS, you will rest awhile in the recovery area. You may feel slightly bloated from the air that was placed in your GI tract, but this will gradually subside. You may have a sore throat which will also subside. Some people develop nausea due to the sedative medications given. Once you are more alert, your doctor will discuss the test's findings with you. If a biopsy was obtained, the doctor will contact you with the results when they become available. Since the effects of the sedative medication may take up to 24 hours to wear off completely, you should plan to go directly home. You will need to have a driver come with you as you will not be allowed to drive for the remainder of the day. Have a light meal and rest for several hours. After sedation has worn off, you may resume your regular diet, but you will not be able to return to work, drive, or operate any dangerous machinery for the remainder of the day. If you did not receive any sedation, you will be allowed to resume your normal activities at discharge.

Text & Images Courtesy of Three Rivers Endoscopy Center
© Dr. Robert Fusco, Three Rivers Endoscopy Center, All Rights Reserved

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