Endoscopic Ultrasound (EUS)

Endoscopic ultrasound (EUS) is a nonsurgical procedure in which endoscopy is combined with high-frequency sound waves (ultrasound) to obtain detailed images of the lining and walls of the upper and lower digestive tract (esophagus, stomach, small intestine, large intestine, and rectum). It can also be used to visualize nearby organs and structures such as the liver, pancreas, bile ducts, and lymph nodes.

EUS is used to diagnose certain conditions that may cause abdominal pain or abnormal weight loss, such as esophageal cancer, gastric (stomach) cancer, pancreatic cancer, and rectal cancer, as well as benign tumors of the upper gastrointestinal tract. It also allows the doctor to obtain biopsies of tumors/lesions found in the tract. EUS can sometimes detect abnormalities or obtain information other imaging tests cannot.

Combined with Doppler imaging, nearby blood vessels can also be evaluated. Minute lesions down to a size of 5 mm may be imaged and consequently biopsied. Organs such as the liver, pancreas, and adrenal glands can easily be biopsied as can any abnormal lymph nodes. This procedure is performed on a regular basis with a low rate of complications (below 1-2%).

Endoscopic ultrasound is highly sensitive for the detection of pancreatic cancer (90-95% sensitivity). EUS with fine needle aspiration (FNA) is very useful in establishing an initial tissue diagnosis of malignancy and determining how far it has spread, reducing the need for surgery and its risks.

How to Prepare for an Endoscopic Ultrasound

If you are having an EUS of the upper gastrointestinal tract, you should not eat anything after midnight or drink anything for 6 hours prior to the procedure.

If you are having an EUS of the rectum or colon, you may need to undergo bowel prep similar to preparing for a colonoscopy. Your doctor will provide you with specific instructions.

Your doctor will let you know if or when you should adjust or stop any medications you take. Because you will be sedated, you will need someone to drive you home after the procedure.

What to Expect

The procedure is performed by gastroenterologists who have had extensive advanced training. It is used mainly in the upper digestive tract but can also be used in the colorectal area. The procedure normally takes less than 60 minutes for an ultrasound only to two hours or more for an FNA, depending on the difficulty of obtaining accurate specimens.

For an EUS of the upper digestive tract, you will be sedated while the doctor inserts the endoscope through the mouth into the esophagus, stomach, and duodenum. For an EUS of the lower digestive tract, the doctor inserts the endoscope through the anus into the rectum and/or colon. You may need to be sedated for this procedure, depending on how much of the colon the doctor needs to examine.

To obtain a biopsy, the doctor inserts a needle into the scope and through the stomach lining into the target area. This procedure is called endoscopic-guided fine needle aspiration (FNA).

A laboratory technician is present at the procedure to prepare the biopsy slides and a pathologist is then called in to let the endoscopist know whether or not he/she is obtaining accurate specimens or to give a diagnosis. All specimens are taken to the lab for further examination, but on occasion a diagnosis may be obtained at the close of the procedure.