Endoscopic ultrasound uses an endoscope with an ultrasound probe incorporated into its tip. This technology enables the physician to examine the layers of the wall of the esophagus, stomach, duodenum and rectum. Structures in the chest, abdomen, and pelvis that are near the digestive tract can be closely examined. EUS provides detailed information about these areas that other imaging studies cannot provide.
When is EUS needed?
EUS is performed for the following indications:
- Staging of gastrointestinal cancers: these include cancers of the esophagus, stomach, pancreas, bile ducts and rectum. EUS is the most accurate method to diagnose the extent of these tumors (staging). Often lymph nodes in the involved area will be sampled with needle biopsy to diagnose lymph node involvement.
- Diagnosis of cancer: EUS is often the best method to diagnose the presence of cancer within the gastrointestinal wall, chest or upper abdomen. Cancers located in the esophageal wall, gastric wall, mediastinum, bile ducts and pancreas can be accurately identified. Needle biopsies of the area are performed under ultrasound guidance to confirm the presence of cancer cells.
- Diagnosis of pancreatic disease: the presence of chronic pancreatitis and pancreatitis can be accurately diagnosed.
How is the procedure done?
For the procedure, you will swallow a thin, flexible, lighted tube called an echoendoscope. An ultrasound probe is incorporated into the tip of this echoendoscope. Right before the procedure, the physician will spray your throat with a numbing agent that may help prevent gagging. You may also receive pain medicine and a sedative to help you relax during the exam. The echoendoscope transmits images of the organs within the chest and abdomen. These structures can include the esophagus, mediastinum, stomach, duodenum, pancreas and bile ducts, and rectum. Cancer can be diagnosed by taking needle biopsies that are obtained under ultrasound guidance.
The physician can see abnormalities, inflammation, benign tumors as well as cancers that do not show up well with standard endoscopy or CT scanning. The presence of cancer and its extent can be confirmed. The physician can obtain samples of tissue (biopsy) with a needle when a diagnosis of cancer needs to be made.
Possible complications of endoscopic ultrasound include bleeding and puncture of the stomach lining. However, such complications are rare. Most people will have nothing more than a mild sore throat after the procedure.
The procedure takes 20 to 60 minutes. Because you will be sedated, you will need to rest at the endoscopy facility for one to two hours until the medication wears off. You will be able to eat after you leave the endoscopy area unless instructed otherwise.
How do I prepare for the examination?
Your stomach and duodenum must be empty for the procedure to be thorough and safe, so you will not be able to eat or drink anything for at least six hours beforehand. Also, you must arrange for someone to take you home-you will not be allowed to drive because of the sedatives. Your physician may give you other special instructions.