Endoscopic Ultrasound (EUS)


Endoscopic Ultrasound (EUS) is a powerful new diagnostic tool that physicians use to examine the lining and walls of the upper and lower gastrointestinal tract and nearby organs such as the pancreas, liver and gallbladder. This procedure gives much more information than endoscopy alone. The procedure involves passing a thin, flexible tube called an endoscope through either the patient’s mouth or rectum to get into proximity of the area of concern. A small transducer within the special endoscope produces sound waves that create a viewable image of the surrounding tissues and organs. In general, EUS is used to determine the cause of symptoms such as abdominal pain and to diagnose diseases of the digestive tract and lungs. For example, EUS can be used to:

  • Diagnose or evaluate Barrett’s Esophagus
  • Evaluate chronic pancreatitis and other masses or cysts of the pancreas.
  • Study bile duct abnormalities including stones in the bile duct or gallbladder.
  • Examine possible bile duct, gallbladder or liver tumors.
  • Study abnormalities of the GI tract lining such as nodules or ‘bumps’ that may be hiding in the intestinal wall covered by normal-appearing lining of the intestinal tract.
  • Evaluate enlarged lymph nodes in the abdomen and chest.
  • Stage cancers of the esophagus, stomach, pancreas and rectum.
  • Stage lung cancer.

When combined with fine-needle aspiration, EUS is a minimally invasive, state-of-the-art alternative to exploratory surgery to obtain tissue samples (biopsies) from abdominal organs and lymph nodes. Physicians also use EUS to guide pseudocyst drainage, injections, and pain managing treatments.

Before the Procedure

If you are undergoing EUS, inform your doctor first about your allergies, especially latex, sedatives, shellfish and iodine. Also discuss your current and past health problems such as heart disease, diabetes, bleeding disorders, lung disease, etc., and if you are currently taking medications that interfere with blood clotting (such as Coumadin®) or platelet function (such as aspirin, ibuprofen, Plavix®, or other NSAIDS). Lastly, if you usually take antibiotics prior to dental work due to heart valve disorders, be sure to inform your doctor so he or she can determine if you should take antibiotics to prepare for your EUS procedure.

EUS is performed with sedation so you will not be able to return to work or to drive for 24 hours. If your procedure is being done in an outpatient setting, this means that you will need someone to take you home.To prepare for your EUS, you will need to have an empty stomach, so do not eat or drink for six hours before the procedure. In the case of a rectal EUS, you will probably need to take some enemas or laxatives. In either case, full instructions will be given to you prior to your procedure.

Procedure Day

Upon arrival at the endoscopy center, the nurse or the doctor will discuss the procedure and answer any questions. You will then be asked to sign a consent form indicating you were informed about the procedure, its alternatives and its risks. You will undress and put on a hospital gown. An IV will be placed in a vein and kept open with a slow drip of IV fluid. This IV will be used to administer the sedatives or other required medication. Deep anesthesia is rarely necessary. You will then be taken into the procedure room. Small electrode patches will be placed on your skin for the monitoring of your blood pressure, pulse and blood oxygen. Sedation will be administered at this time.

Once sleepy, the special endoscope will be inserted and the procedure started. Because of the sedation, you will only feel minimal discomfort, if any, during the entire procedure. Everything will be done to help you be as comfortable as possible throughout the entire procedure. The physician will observe the inside of your GI tract on a TV monitor and the ultrasound image on a separate screen. Depending on the abnormality (if any) identified, your doctor may elect to collect some tissue samples during the procedure. This can be done with a biopsy forceps or via the fine needle aspiration (FNA) technique. If a fluid collection is seen, it can be suctioned through the scope, and the fluid is sent for analysis. Occasionally, if there is a large cyst in the pancreas that needs drainage, your doctor may place a stent through the stomach or small bowel into the pancreatic cyst. This process is called a cyst-gastrostomy or a cyst-duodenostomy. The entire procedure generally takes 30 to 90 minutes depending on the complexity and whether fine needle aspiration (FNA) is performed.

After the procedure is completed and once you are fully awake, the doctor will discuss with you the findings of the procedure. Barring any rare complications, when you are fully awake, your companion will be able to take you home where you should rest for the remainder of the day. Light meals and fluids are allowed. You may experience bloating from air and water used during the procedure, but it will only be temporary. If you experience a sore throat, salt-water gargles or lozenges may provide relief.

Potential Complications

Like other endoscopy procedures, EUS is safe and well-tolerated, but no procedure is completely without risk. Sometimes patients can develop reactions such as hives, skin rash or nausea to the medications used during EUS. A lump may appear in the area of the vein where the IV was placed, which usually resolves over time. Should it persist, you should contact your physician. The main serious complication is perforation (making a hole in the intestinal wall) that may require surgical repair. However, perforation is quite rare and all precautions are taken to avoid it. When FNA is performed, complications occur more often but are still uncommon. Passing a needle through the gut wall may cause minor bleeding. If unusual bleeding occurs, the patient may be hospitalized briefly for observation, but blood transfusions are rarely needed. Infection is another rare complication of FNA. Infection can result from aspiration of fluid from cysts. Antibiotics are given during the procedure and for several days after to prevent infection from occurring. If the FNA is performed on the pancreas, pancreatitis (inflammation of the pancreas) can rarely occur. Pancreatitis calls for hospitalization, observation, rest, IV fluid, and medication for abdominal pain. It usually resolves spontaneously in a few days. Contact your doctor immediately if you experience severe abdominal pain, difficulty swallowing, fever, vomiting up blood, bloody bowel movements, or extreme dizziness/weakness, after your procedure. Early recognition of possible complications is important.


On some occasions it may be necessary to follow up with the endoscopist to review the exam findings and discuss future treatment or diagnostic testing. In all cases, copies of your reports and biopsy results will be forwarded to your primary care physician (as well as any designated specialists) who would direct your health care needs.

For more information
To learn more about this topic, visit:

UCSF Gastroenterology

Mayo Clinic