Medically reviewed by Drugs.com. Last updated on Jul 6, 2022.
Endoscopic ultrasound (EUS) is a minimally invasive procedure to assess diseases of the digestive (gastrointestinal) tract and other nearby organs and tissues. Endoscopic ultrasound combines the use of a thin, flexible tube (endoscope) inserted into the gastrointestinal tract and a device that uses sound waves to create images (ultrasound).
The high-frequency sound waves produce detailed images of the digestive tract and surrounding organs and tissues, including the lungs, pancreas, gall bladder, liver and lymph nodes.
An endoscopic tube may also have a small needle to remove fluid or tissue samples (biopsy) for examination in a lab. This procedure is called EUS-guided fine-needle aspiration or EUS-guided fine-needle biopsy. Other EUS-guided procedures can be used to drain fluid from a lesion or inject a drug at a specific site.
During an endoscopic ultrasound of the pancreas, your doctor inserts a thin, flexible tube (endoscope) down your throat and into your stomach. An ultrasound device at the end of the tube emits sound waves that generate images of your digestive tract and nearby organs and tissues.
Why it's done
EUS can create images of the lining and walls of any organ along the route of the gastrointestinal tract. An EUS device placed down the throat can capture images of the esophagus, stomach and parts of the small intestine. An EUS device inserted through the anus captures images of the rectum, parts of the large intestine (colon) and surrounding tissue such as lymph nodes.
Internal organs or nearby structures can also be visualized, including the following:
- Lymph nodes in the center of the chest
- Gall bladder
- Bile ducts
EUS with fine-needle aspiration or other instruments can also reach these other organs. For example, a needle can pass through the wall of the esophagus to nearby lymph nodes. Similarly, a needle can pass through the wall of the stomach to deliver medication to the pancreas.
EUS and EUS-guided procedures can be used for the following:
- Assess damage to tissues due to inflammation or disease
- Determine whether cancer is present or has spread to lymph nodes
- Assess how much a cancerous (malignant) tumor invades tissues
- Determine how advanced cancer is
- Provide more-detailed information about lesions identified with other imaging technologies
- Extract fluid or tissue for diagnostic testing
- Drain fluids from cysts
- Deliver therapies to a targeted region, such as a malignant tumor
EUS is generally safe when performed at a center with an experienced and expert health care team. The procedure is usually performed by a medical doctor who specializes in the digestive system (gastroenterologist) and has specific training in EUS procedures.
Your doctor will discuss with you the risk of complications from EUS. These risks, which are most commonly associated with fine-needle aspiration, may include:
- Tearing (perforation) of an organ wall
- Pancreatitis, if fine-needle aspiration of the pancreas is done
You can reduce your risk of complications by carefully following your doctor's instructions for preparing for EUS.
Call your health care provider immediately or go to an emergency room if you experience any of the following signs or symptoms after the procedure:
- Severe or persistent abdominal pain
- Neck or chest pain
- Severe nausea or vomiting
- Vomiting blood
- Black or very dark-colored stool
How you prepare
Your doctor will give you specific instructions to prepare for your EUS. Instructions will include the following:
- Fasting. You'll likely be asked to fast for at least six hours before the test to ensure your stomach is empty.
- Colon cleansing. If the EUS will be performed through the rectum, you'll be directed to use a colon cleansing solution or to follow a liquid diet and use a laxative before the procedure.
- Medication. Tell your doctor about all prescription and nonprescription medications you take, as well as herbal remedies and dietary supplements. Follow the instructions on which medications you can take and which you need to stop taking before the procedure.
- Travel. Medication to help you relax or sleep (sedative) or anesthesia can impair your coordination and judgment after the procedure. Arrange for someone to drive you home and stay with you the rest of the day.
What you can expect
If you are given anesthesia, you won't be conscious during the procedure. If you're given a sedative, you may feel a slight discomfort, but many people fall asleep or are not alert during the procedure.
You'll likely lie on your left side during the procedure. The doctor feeds a thin, flexible tube (endoscope) through your throat or through your rectum, depending on the purpose of the procedure.
The endoscope has a tiny ultrasound transducer at the end. Any other instrument used during the procedure, such as a needle for a biopsy, also passes through a channel in the endoscope.
EUS usually lasts less than an hour. An EUS-guided procedure may last longer.
You may have a sore throat after an upper EUS procedure. Throat lozenges may provide relief.
A specialist in digestive diseases (gastroenterologist) or lung disease (pulmonologist) with special training in EUS will interpret the EUS images. A doctor trained in analyzing biopsies (pathologist) will report the test results if you have fine-needle aspiration. Your doctor will discuss any important findings and next steps with you.