What is an Endoscopic Ultrasound?
Digestive endoscopic ultrasound, or Echoendoscopy, is a test that combines endoscopy and high resolution ultrasound. The apparatus used to carry out this test is called an echoendoscope. It is a thin, flexible endoscope, especially equipped with a miniature ultrasound probe (transducer) that is attached to the end of the apparatus, which allows the ultrasound to be performed inside the digestive tract.
The probe may be inserted via the mouth (Endoscopic Ultrasound of the Upper Digestive Tract, to examine the oesophagus, stomach and duodenum) or the anus (Endoscopic Ultrasound of the Lower Digestive Tract, to examine the colon and rectum). The ultrasound transducer allows detailed images of the various layers of the wall of the gut throughout its thickness to be obtained, and allows close examination of other structures surrounding the digestive tract, including lymph nodes, blood vessels, and, in the case of High Digestive Endoscopic Ultrasound, the mediastinum, lungs, liver, gallbladder, biliary tract and pancreas.
While classical endoscopy only allows the mucosa to be observed, through the ultrasound transducer placed inside the lumen, echoendoscopy allows all the layers of the wall of the digestive tract, and any pathology found there, to be examined.
High Digestive EUS can be used to diagnose conditions of the oesophagus, stomach and duodenum, also allowing adjacent organs such as the gallbladder, the bile ducts and the pancreas, to be examined.
Why is Endoscopic Ultrasound necessary?
Endoscopic Ultrasound has important implications in the diagnostic approach and treatment of various clinical situations, being today considered an indispensable technique in all advanced endoscopy centres.
Usually, an Endoscopic Ultrasound is requested following endoscopic examinations and/or previous imaging, with the aim of clarifying the findings of these examinations or complementing investigations. Among the most common indications for this examination is the staging of tumours of the digestive system, the evaluation of subepithelial lesions of the gut wall and evaluation of biliary and pancreatic diseases.
For example, Endoscopic Ultrasound allows the extent of the spread of certain tumours of the digestive tract or respiratory tract to be determined, by accurately assessing the depth of tumour invasion into the wall and whether there is already spread to nearby lymph nodes or nearby vital structures, such as major blood vessels.
On the other hand, Endoscopic Ultrasound also allows us to clarify whether a bulging gut wall corresponds to a compression caused by a neighbouring organ, or an injury to the wall itself “camouflaged” by a normal-looking mucosa; in this case, the Endoscopic Ultrasound allows us to characterise the lesion, accurately assessing its size, source layer in the wall and various morphological characteristics, suggesting the most likely diagnosis. In some patients, biopsies may be obtained under ultrasound control (punch biopsy, fine needle aspiration) that complement the investigation.
In relation to biliary and pancreatic disease, EUS can be applied in the investigation of tumours of the pancreas or bile ducts, calculi (stones) of the gallbladder or bile ducts, the study of chronic pancreatitis and pancreatic liquid collections, among others. A possible therapeutic application of EUS involves precisely, in selected cases, drainage of cystic lesions of the pancreas.
What preparation is required?
For Endoscopic Ultrasound of the Upper Digestive Tract, it is necessary for the patient to refrain from eating or drinking for six hours prior to the examination.
For Endoscopic Ultrasound of the Lower Digestive Tract, the doctor will indicate whether to take an oral solution for cleaning the intestines (similar to the preparation for a colonoscopy), or whether it is sufficient to use laxatives or enemas before the test.
What should be done in relation to usual medication or allergies?
Generally, you can continue to take all your usual medication until the day before the examination. However, please tell your doctor about all medicines you are taking and any allergies of which you are aware. There may be a need to suspend or adjust the dose of anticoagulants (like warfarin or enoxaparin) or antiplatelet agents (such as clopidogrel). Taking insulin may also need to be adjusted. Check in advance with your doctor whether to suspend or adjust any medication you take regularly. Check the medicine you should take on the morning of the examination, and take only the necessary medication with a small amount of water.
If you are allergic to any medication or to latex, you should tell your doctor before the examination.
Is it necessary to take antibiotics?
It is not usually necessary to take antibiotics before or after the EUS. However, antibiotics may be prescribed in the case of specialised tests that involve taking biopsies or draining collections of fluids or cysts guided by EUS.
What does the Endoscopic Ultrasound involve?
During the Endoscopic Ultrasound of the Upper Digestive Tract, a nozzle is placed in the patient’s mouth and a nasal cannula will supply oxygen during the examination. A sedative is usually administered intravenously to help you relax. Most commonly, the examination is executed with the patient lying on his or her left side. After initial sedation, the doctor will pass the echoendoscope through the mouth, oesophagus and stomach, progressing to the duodenum. The echoendoscope does not interfere with breathing. The duration of the test varies, taking on average about 30 minutes. However, if biopsies of a lesion need to be performed or a cyst drained during the Endoscopic Ultrasound, the procedure will take longer, and may exceed two hours. When the examination is over, many patients do not remember anything about it. Most consider it only slightly uncomfortable, and many fall asleep during it.
An Endoscopic Ultrasound of the Lower Digestive Tract may often be performed safely and comfortably without the prior administration of any medication. However, a sedative may be given if it is an extended examination or the examination involves the echoendoscope travelling a significant distance inside the colon. The examination is executed with the patient lying on his or her left side, with his or her back to the doctor. The duration of the test varies, taking on average about 30 minutes.
What happens after the Endoscopic Ultrasound?
The EUS does not usually involve the hospitalisation of the patient, although this may be necessary in some cases. If you received sedatives, you will be monitored in the recovery area of the unit where the examination was carried out, until most of the effects of the medication have worn off. Usually, recovery after the procedure requires a rest period of less than one hour, after which you may be discharged. If you have had an Endoscopic Ultrasound of the Upper Digestive Tract, you may feel mild discomfort in the throat. You can also feel your abdomen bloated due to the air and water introduced through the echoendoscope during the examination.
Your doctor may give you some preliminary information about the test results, although the final results of some tests, including biopsies, may take several days.
If you received sedatives, you will not be allowed to drive after the examination, even if you do not feel tired. You should therefore arrange your means of transport in advance. You are also advised to be accompanied by someone you trust who can provide any assistance that might be necessary, since the medication may affect your ability to think, decide and your reflexes for the rest of the day. You may eat and drink after leaving the endoscopy unit, unless you are given instructions to the contrary.
What are the possible complications of Endoscopic Ultrasound?
AEndoscopic Ultrasound is usually a very safe and well tolerated procedure. Although complications can occur, they are rare.
In the case of Endoscopic Ultrasound of the Upper Digestive Tract, you may feel mild discomfort in the throat for about a day. You may purchase a topical anaesthetic to relieve these symptoms over the counter at a chemist’s.
Although rare, some potential risks of EUS include reactions to sedation, aspiration of gastric contents into the lungs and complications due to prior heart or lung disease, with some cases of cardio-respiratory depression being reported.
The possibility of complications increases slightly if biopsies are performed during the examination, as there is an increased risk of bleeding or infection. These risks have to be balanced against the potential benefits of the procedure and the risks of other alternative approaches. One serious but extremely rare complication of EUS is perforation; this can sometimes be resolved with conservative medical therapy or by endoscopic techniques, however the need may arise for surgery.
If, after discharge, you feel any new complaint that worries you, contact the Endoscopy Unit where the procedure was performed or the Accident and Emergency department of the nearest Hospital.
This information is only intended to provide general guidance, and is not a substitute for specific medical advice. It is essential that you discuss your specific medical condition with your doctor.