Using Sound Waves for Enhanced Imaging
Endoscopic ultrasonography (EUS) is a minimally invasive medical procedure that combines endoscopy with ultrasound to provide your doctor with clear images of the gastrointestinal (GI) tract and adjacent internal organs to encompass:
- Lining of the stomach
- Walls of the upper and lower GI tracts
- Gallbladder, pancreas, liver and lymph nodes
These detailed images serve as a better diagnostic tool than other imaging tests, such as CT scan, to allow your doctor to better assess digestive disorders and develop the right course of treatment.
How EUS Works
In an EUS procedure, your doctor will insert a thin, flexible tube known as an endoscope through your mouth or anus and guide it to the area of concern. The specialized endoscope has an ultrasound attachment that uses high-frequency sound waves to produce clear, detailed images of your digestive tract and nearby organs.
Reasons for EUS
Regarding digestive health, EUS is regularly used to determine the cause behind conditions such as abdominal pain, jaundice or unexplained weight loss by looking at the upper GI tract, which includes the esophagus, stomach and duodenum, and the lower GI tract, which is the colon and rectum. EUS also can be used to provide a definitive diagnosis for diseases involving the pancreas, bile duct, adrenal glands, liver, lymph nodes and gallbladder, or to assess abnormalities found in a prior endoscopy, such as lumps or polyps.
Role of EUS in Diagnosing and Treating Cancer
With the capability to accurately evaluate how deep a cancerous mass is and whether it has spread to adjacent lymph glands or other organs, EUS can help doctors assess some cancers of the digestive and respiratory systems. EUS also can find small cancers in the pancreas or other digestive organs that other diagnostic imaging, such as CT or MRI scans, may miss. And once a cancer is found, EUS can be used to perform biopsies so doctors can make a conclusive diagnosis and develop an appropriate plan of care.
Pancreatic mass seen on EUS (left), with cytology from the biopsy of the mass showing cancer cells (right).
Other Treatments EUS Offers
EUS can be used to treat infection in the pancreas by placing a small metal or plastic tube called a stent in the stomach wall to allow the infection from the pancreas to drain into the stomach. EUS also can be used to treat pain from pancreatic cancer by injecting medication to numb the nerves near the pancreas. In select instances, using chemotherapy or current energy, small tumors can be treated successfully using EUS.
How To Prepare for EUS
For EUS of the upper GI tract, you cannot eat or drink anything (not even water) for about six hours prior to the procedure. Your doctor will give you specific instructions on when to start fasting.
For EUS of the lower GI tract, preparation will include either drinking a special cleansing solution or following a clear liquid diet in combination with enemas. Your doctor will give you specific instructions. If you do not precisely follow your doctor’s instructions, the procedure may have to be postponed.
Most medications can be taken as usual until the day of your procedure. Be sure to tell your doctor about all medications you are taking as well as any medication allergies. Anticoagulant medications (blood thinners) may have to be adjusted prior to the procedure. Consult with your doctor ahead of time regarding these medications. Also check with your doctor about which prescribed medications can be taken the morning of your procedure, and only take those with a sip of water.
If you have a latex allergy, please let your doctor know prior to your EUS procedure so that any necessary precautions can be taken.
It usually is not necessary for you to take any antibiotics prior to or after an EUS procedure; however, if you normally take antibiotics before dental procedures, let your doctor know. It may be determined that you should take an antibiotic to help prevent an infection. If your doctor is performing specialized EUS-guided treatment, such as draining a cyst or fluid, antibiotics may be ordered. Be sure to tell your doctor about any allergies to antibiotics that you have.
What To Expect During Your Procedure
For an EUS of the upper GI tract, you will be given intravenous (IV) sedatives to help you relax. The procedure will most likely begin with you lying on your left side. Once you are sedated, your doctor will insert the endoscope through your mouth and guide it through the esophagus and stomach to the duodenum. You will be able to continue to breathe normally with the endoscope in place. The procedure itself typically lasts from 10 to 60 minutes. Most patients consider the exam only slightly uncomfortable, and many fall asleep during the procedure.
You will be sedated for an EUS of the lower GI tract, particularly if the procedure is planned to take longer or the area to be evaluated is a considerable way into the colon. You will begin by lying on your left side. Most EUS lower-GI procedures last from 10 to 45 minutes.
What To Expect After Your Procedure
Since you are sedated for the procedure, you will be kept in the recovery area and monitored until effects of the medication have diminished. If you had an upper GI procedure, your throat may feel a little irritated, and you may feel a bit bloated because of air and water introduced during the procedure. Unless instructed otherwise, you will be able to eat after leaving the procedure area.
You will not be allowed to drive after the procedure, even if you are not feeling tired. Make sure you arrange for a ride home and someone to stay with you after the procedure; you may be feeling the effects of the sedatives you received for the rest of the day.
Typically, you will receive the results of the exam from your doctor on the same day. However, some test results may take several days and will be sent to your referring doctor.
Possible Complications of EUS
Doctors with the Bayfront Health Digestive Health Institute are specially training and experienced in performing EUS procedures, and complications or adverse events are extremely rare. If a biopsy was taken, there may be some bleeding at the biopsy site; it is typically minimal, and you will not need any treatment or follow-up care. Your throat may feel sore for a day or two following the procedure; anesthetic-type, over-the-counter lozenges can help. While uncommon, possible complications from EUS can include:
- An adverse reaction to the sedative given (While very rare, this is a concern for patients with severe heart or lung disease.)
- Aspiration of stomach contents into the lungs
- A puncture or tear in the lining of the intestine that may require surgical repair
The risk of complications from EUS increases slightly if a needle biopsy is done. Risks must be weighed against the expected benefits of the procedure as well as the possible risks of alternative approaches to diagnose and treat your condition.
Artificial Intelligence in EUS
Doctors at the Bayfront Health Digestive Health Institute are investigating the use of artificial intelligence (AI) to more accurately determine whether a mass or lesion identified at EUS is benign or malignant. Currently, EUS-guided biopsies have a more than 95 percent rate of accuracy. Doctors at the institute are trying to increase that diagnostic rate by integrating AI within an EUS procedure. This technology is based on a convolutional neural network that guides management of highly challenging and complex cases. This experimental technology is currently not available at any other center in the world.