Introduction What is an ERCP? - An ERCP is an 'Endoscopic Retrograde Cholangio-Pancreatography'.
- This is a serial x-ray-based investigation of the pancreatic & biliary tree.
- The procedure involves the use of a contrast medium prior to the procedure to highlight the anatomy on the x-ray.
- Remember to use the word 'contrast' and not 'dye' - dyes are for clothes!
Anatomy Revise the basic anatomy of the region: the 2 hepatic ducts drain bile from the liver. These join to form the common hepatic duct, which combines with the cystic duct from the gallbladder to form the common bile duct. The pancreatic (exocrine) duct drains pancreatic secretions from the pancreas. Both open at the second part of the duodenum (D2) at the Ampulla of Vater. When is ERCP performed? The purpose of this investigation is to detect pathology by imaging in the biliary tree. This involves: - Gallstones stuck in the biliary tree. It may also be possible to image tumours, as well as to visualise other causes of decreased patency of the biliary tree (eg. biliary cirrhosis).
- Jaundice is the common presenting symptom in patients with the above pathology.
- ERCP can also be used to investigate other causes of unexplained abdominal pain.
ERCP is both a diagnostic and therapeutic tool. It can be used to relieve jaundice by the removal of gallstones from the bile ducts by the placement of a plastic tube (stent) across narrowings in the ducts. In addition, the procedure of 'sphincterotomy' can be used to dilate the Ampulla of Vater to allow stones to pass.
How is it performed? In a clinical scenario, always remember to do the basics first: introduce yourself, check the patient's identity and explain what you are going to talk to them about. - An ERCP is performed in the radiology department/suite. The patient needs to fast for at least six hours.
- The procedure begins by spraying the back of the throat with a local anaesthetic spray to anaesthetise the area. Mention to the patient that this may make swallowing difficult, and they should be careful with hot drinks until the anaesthetic has worn off to avoid accidental burns.
- A Venflon is sited, and a sedative drug is injected. This is usually a benzodiazepine such as Midazolam. Explain that this is not a 'full' anaesthetic, but that it will make the patient feel very sleepy. Midazolam also causes amnesia, so the patient will probably not recall the procedure. It is probably best to mention this as an advantage (as it is not a particularly pleasant procedure) rather than as a disadvantage (it is also rather similar to the date-rape drug).
- The ERCP uses a modified endoscope that is placed into the mouth. The patient will be asked to try and 'swallow' it. Explain that it will feel rather like swallowing a large piece of food.
- The patient by this stage will be unaware of 'what happens next'. For their information, the endoscope is passed through into the duodenum. Once there, a thin tube will be passed from the endoscope through the Ampulla of Vater into the ducts. The contrast medium is then injected into the duct. Throughout this process, x-ray pictures are continually taken. The ERCP tube is radio-opaque and so 'shows up' on the x-ray. The contrast helps define the biliary anatomy.
- If there is a stone in the bile duct, this can be removed a sphincterotomy (dilating the lower end of the duct and 'dragging' the stones out). If there is a narrowing in the bile duct, a plastic tube (stent) will be inserted to allow the bile to drain more freely into the duodenum.
- After the procedure, the patent will continue to feel drowsy for several hours. If a stone has been removed or a stent inserted they may need to stay in hospital overnight. The patient must not drive a car, operate machinery, or drink alcohol until the next day. They should arrange for someone to collect them after the procedure.
- After you have explained the procedure, always ask the patient if they have any questions or concerns.
Risks & contraindications As with most 'invasive' procedures, patients in the UK will be required to sign a standardised consent form prior to the procedure. In order to do this, the patient must be competent, the consent must be based upon comprehensive information, and must be free from coercion (should not be forced). Bear in mind though, that despite this (and rather bizarrely), a consent form is not a legally valid document! In any case, you should discuss the following risks with patients prior to an ERCP: - It is generally considered important to highlight risks that have a >1% chance of occurrence.
- Diagnostic ERCP is a safe procedure. In rare cases, patients may be develop allergic reactions to the contrast medium. There is also a small risk of inflammation of the pancreas (pancreatitis), which occurs in about 1% of procedures. There is also the small risk of rupture (perforation) of any of the tract.
- Therapeutic ERCP is more like a surgical procedure. Although it is still safe, a greater proportion (about 3% of patients) may experience complications. Again, the major ones are infection, bleeding and pancreatitis. Most people, however, do recover completely with medical treatment.
Contraindications: Note that in pregnancy, the contrast medium can be teratogenic and should be avoided. The dose of contrast may also need to be adjusted in patients with liver, heart or kidney disease.
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