An endoscopic ultrasound (EUS) uses high-frequency sound waves to create diagnostic images of the gastrointestinal tract or lungs. The sound waves are transmitted by a transducer attached to the tip of the endoscope and projected onto a video screen. EUS has the advantage of being a minimally invasive, outpatient procedure that nonetheless provides an accurate, detailed view of the interior of the digestive tract, the chest, and the lymph nodes.
In most cases, the endoscope is inserted through the patient’s mouth, but when it is necessary to examine the rectal area, the endoscope is inserted through the anal opening. Either way, the EUS allows the doctor to perform certain diagnostic or treatment tasks. When combined with a procedure called fine-needle aspiration, EUS provides a minimally invasive alternative to exploratory surgery in order to obtain tissue for biopsy.
Reasons For An EUS
The reasons for an EUS may be diagnostic only or may involve collecting tissue for analysis.
Most commonly, an endoscopic ultrasound is used to detect the underlying causes of abdominal or chest pain or to evaluate the progression of digestive or lung disease. Conditions that may be diagnosed or evaluated using an EUS include:
- Barrett’s esophagus
- Fecal incontinence
- Malignancies of the gastrointestinal or lung cancer
- Neuroendocrine tumors
- Pancreatitis and pancreatic cysts
- Rectal fistulas
- Stones in the bile ducts
The EUS frequently follows an MRI or CT scan as a further investigative tool.
In addition to providing clear and definitive diagnoses, including determining the stage of a cancer or the extent of any metastasis, EUS is used in a number of treatment procedures which may include:
- Draining pseudocysts
- Draining abnormal fluid accumulation from the abdomen (ascites)
- Delivering medication directly to an internal organ, such as the pancreas
Endoscopic ultrasounds are tolerated well by most patients, but may not be possible to perform on patients who have had certain types of bariatric surgery.
Preparation For An EUS Procedure
Before undergoing an EUS, patients have to fast so their gastrointestinal tract is empty. If they are preparing for a rectal ultrasound, they will also need to take a laxative or an enema before the procedure.
If there is the possibility that a fine needle biopsy will be taken, patients usually have to temporarily discontinue the use of blood thinners prior to the procedure. An analgesic will be applied to the throat or rectum to prevent discomfort. Patients are sedated for the endoscopy and therefore must arrange for someone else to drive them home afterwards.
Risks Of An Endoscopic Ultrasound
EUS is generally considered a safe procedure. Even so, there are risks inherent in any medical procedure. In this case, the risks may include one or more of the following, depending on where the endoscope is inserted and upon whether a fine-needle aspiration is performed.
- Perforation of the throat, rectum, or intestinal wall
Symptoms that may signal an emergency following an EUS include fever, shortness of breath, chest pain, severe abdominal pain, difficulty swallowing, vomiting or black stool.