Endoscopic Ultrasound (EUS)
The endoscope (flexible tube) for endoscopic ultrasound (EUS) has a small ultrasound scanner at the tip. The test is commonly performed with sedation.
There are two kinds of EUS – radial and linear. A radial EUS is performed for diagnostic reason whereas a linear EUS may be done for both diagnostic and therapeutic reasons.
Common Reasons for the Test:
- To diagnose the stage of oesophageal (gullet) cancer
- To look for sludge or minute stones (microlithiasis) in the bile ducts and gallbladder (biliary system)
- To obtain detailed picture of an abnormality or abnormal area in the upper gastrointestinal (GI) tract or pancreas/ biliary system, that may have been found by another test
- To obtain detailed picture of an abnormality and take some tissue or cyst fluid samples (core biopsies or fine needle aspirate) in the upper GI tract or pancreas/ biliary system, that may have been found by another test
- To aspirate a pancreatic cyst or drain a pseudocyst (with a cyst-gastrostomy and stenting). The latter normally involves x-ray and is performed in the radiology department
The EUS test complements other imaging tests such as computed tomography (CT), Positron emission tomography CT (PET-CT) or MRI scans to increase certainty of a correct diagnosis. It is sometimes possible for an abnormality in the upper GI tract/ pancreas or pancreatic cyst to be sampled or drained via a needle puncture through the skin (percutaneous) or stomach wall respectively under imaging guidance. The disadvantages include a small risk of tumour seeding along the needle track.
Preparing for the Test
On the Day of Test
In the Endoscopy Room
Drugs Commonly Used for the Test
Topical spray - Local anaesthetic throat spray
Injection - Sedatives (benzodiazepine, midazolam)
- Pain killer (morphine, commonly pethidine or fentanyl)
Patient Position During the Test
Left lateral (see picture 1).
Can I Watch the Test?
This is not feasible as the head position faces away from the video and/ or x-ray (fluoroscopy) monitors and the moderate deep sedation administered during EUS.
You won’t feel any pain from having some biopsies taken or fine needle aspiration. There is no significant discomfort associated with the puncture/ drainage of a pancreatic pseudocyst that involves an electrically heated wire (diathermy) passed through the endoscope.
Injection of additional sedative or painkiller (morphine) drugs will be given as necessary during the tests for adequate control of pain or discomfort.
In diagnostic EUS, the complications of perforation (tear of the linings of oesophagus, stomach or duodenum) or bleeding occur extremely infrequently (less than 1 in 1000 cases).
Endoscopic ultrasound to perform core biopsies or fine needle aspiration of cyst slightly raises the risk of bleeding or infection. Antibiotics injection may be given to help reduce infection risk for cyst aspiration.
If there is any suspicion of the perforation or bleeding complication during or straight after the test (in recovery), patients will be admitted for close monitoring and/or treatment.
Specialist Endoscopies and more . . .