Endoscopic Ultrasound (EUS)

Updated: Jul 4, 2018

Dr. Tim Chen is a gastroenterologist at Pacifica Digestive Health. He is also the Vice President and was one of the co-founders of Pacifica Digestive Health. His clinical interests include therapeutic endoscopy, hepatitis, inflammatory bowel disease, and esophageal motility disorders.


What is an Endoscopic Ultrasound?

EUS of the esophagus (Credit: By Ktg usa from Wikimedia Commons)

An Endoscopic Ultrasound (EUS) uses an endoscopic procedure (a long, finger-width flexible tube with a camera on the end) to view the throat, stomach and small intestine. The scope is used with an attached ultrasound device that produced sound waves to create visual images of the pancreas and bile ducts. This procedure can be used to view the upper or lower GI tract.


What is the Purpose of Endoscopic Ultrasound?


An EUS is usually carried out after your doctor has found an abnormality in a prior endoscopy study, x-ray test or CT scan. It allows the doctor to see ver detailed ultrasound images of the abnormality or lesion. The following are cases that may use an EUS:

  • Cancer staging – this describes the size of the tumor and gives details of whether it has spread to adjacent lymph nodes or other body parts, helping your doctor plan for further treatment. This includes cancers of the esophagus, pancreas, lungs and any other that may have spread from other organs.

  • To investigate lesions in the wall of the GI tracts – Sometimes, small nodules may form on the walls of the GI tract, these may be benign or precancerous. EUS can give your doctor detailed pictures of the five layers of the bowel wall and depend on which layer the lesion is on, he may take a biopsy of the lesion. This means taking a small specimen for investigation under a microscope.

  • To check the increase for cysts or chronic pancreatitis.

  • To check for lesions in the bile ducts, gallbladder, and liver.

  • To determine the cause of fecal incontinence.


How Do You Prepare for an Endoscopic Ultrasound?


Preparation for an EUS depends on whether it is an upper EUs or lower. Although similar, there are some differences you should note. Ask your doctor which of the two you are scheduled for so you can adequately prepare. Some of the common things you can prepare for include:

  • Disclosing all medication you are currently on and any allergies.

  • Disclosing any pre-existing conditions and diseases.

  • Have someone drive you home after the procedure.

For an upper EUS:

  • Do not eat any solids after midnight the night before the procedure.

  • You may need to avoid drinking any liquids for up to six hours before the procedure depending on the medication that will be used.

For a lower EUS:

  • You will need to take a bowel prep to cleanse your colon before the procedure. This may be an enema or a full colonoscopy-type prep.

  • Follow your doctor’s instructions on what and when to eat.


What to Expert During an Endoscopic Ultrasound?


During an EUS, you will be given medicine to block pain and make you relaxed and sleepy. A plastic bite block and nasal cannula may be used. The back of your throat may be sprayed to numb it. An EUS scope will be inserted through your mouth into your esophagus and into your stomach and duodenum as you lie on your left side. The doctor will study the EUS scope images and ultrasound at the same time. In some cases, he may need to take a sample of tissue using Fine Needle Aspiration (FNA) to do a biopsy (examination of a tissue sample under a microscope).


A lower EUS does not necessarily need any medication to block pain unlike an upper EUS procedure. In both cases, the procedure can be carried out in an outpatient clinic or in a hospital, depending on the severity of the case. You feel a sore throat coming, bloating or swelling for up to 24 hours after the procedure but this should go away. Your doctor will let you know when you can collect the test results of the biopsy or arrange for a review.


What Are the Risks and Complications of Endoscopic Ultrasound?


In general, endoscopic ultrasound is a very safe procedure, with complications occurring in less than 1% of patients. Most complications are non-life threatening and may include:

  • Medication reactions

  • Bleeding with biopsies and fine needle aspiration

  • Perforation or puncture of the esophagus, stomach, small intestine, or rectum

  • Any of these complications may require a blood transfusion, more diagnostic testing, procedures, or hospitalization.


Although these complications are uncommon, it is very important that the patient contact the doctor's office immediately if symptoms arise after the procedure such as worsening abdominal pain, bleeding, or fever.


Like any other test, there is a small, accepted risk that abnormalities including cancers can be missed at the time of endoscopic ultrasound. It is important to inform your doctor of new or persistent symptoms, and continue to follow-up as instructed.


What to Expert After an Endoscopic Ultrasound?


After the procedure, a doctor or nurse will review the results with you and give further recommendations, as well as let you know what and when you can eat and drink. You should plan to resume your normal activities 24 hours after your exam. You may experience mild soreness in your throat and mild abdominal cramps. These issues should clear completely after 24 hours. However, you if have more severe or persistent symptoms lasting longer than 24 hours, be sure to inform your doctor.

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