Endoscopic retrograde cholangiopancreatography

Endoscopic retrograde cholangiopancreatography (ERCP) is used both in the diagnosis and the treatment of many pancreatic and biliary diseases. It was first used in the 1970s at which point its main use was in diagnosis. Now, its use is mostly as a therapeutic tool.

Indications¹

• Choledocholithiasis (eg, gallstones in the common bile duct (CBD) and microlithiasis).

• Acute pancreatitis due to biliary obstruction, sphincter of Oddi dysfunction or idiopathic, recurrent cases.

• Detection of pancreatic divisum (more common in patients who develop pancreatitis but may not necessarily be causal).

• Diagnosis of pancreatic and biliary malignancy. Endoscopic ultrasound provides an acceptable option in many cases and can be used as a triage procedure to determine which patients should proceed to ERCP.

• Palliative therapy for inoperable pancreaticobiliary malignancies - eg, drainage procedures.

• Dilatation of benign strictures - eg, following orthoptic liver transplantation.

• Chronic pancreatitis - there is a role for dilatation of strictures or stent insertion.²

• Manometry measures in sphincter of Oddi dysfunction.

ERCP provides detailed and accurate information of the pancreaticobiliary system in cases which cannot be diagnosed by endoscopic ultrasound. It also provides a less invasive option than open surgery for the management of several pancreatic conditions. ERCP has evolved from a purely diagnostic tool to a predominantly therapeutic procedure.

In cases where there is doubt regarding the diagnosis or presence of biliary obstruction, further imaging should be performed first. This may include magnetic resonance cholangiopancreatography (MRCP) if biliary obstruction alone is suspected, or endoscopic ultrasound (EUS) in other conditions.

ERCP done by experienced endoscopists is a safe procedure during pregnancy. Radiation-free techniques appear to reduce the rates of nonpregnancy-related complications, but not of fetal and pregnancy-related complications.³

ERCP and choledocholithiasis

One method for determining who should have an ERCP is to classify patients into low-risk, intermediate-risk or high-risk.

• Low-risk patients should proceed to laparoscopic cholecystectomy without further intervention or imaging procedures.

• Intermediate-risk patients include those with features, such as previous history of cholangitis or pancreatitis, slightly abnormal LFTs (eg, raised ALP but less than twice normal), dilated CBD between 8-10 mm. This group of patients should have further tests (eg, endoscopic ultrasound) before deciding on further intervention.

• High-risk patients include those with recent cholangitis, recent acute pancreatitis, jaundice, abnormal LFTs (ALP more than twice normal) and dilated CBD >10 mm. This group will usually benefit most from ERCP. However, even a third of these patients will fail to have a stone on ERCP and further investigation may be needed.

ERCP and acute pancreatitis

• Acute pancreatitis post-ERCP is a potentially fatal complication that can be as high as up to 30% in high-risk patients.⁴

• However, some patients with severe acute pancreatitis with evidence of biliary tract obstruction have an ERCP.

• At ERCP, sphincterotomy may be performed to remove duct obstruction - eg, gallstone.

• There is a risk that pancreatitis may be worsened. There is no role for early ERCP in patients with (predicted) mild biliary pancreatitis to improve outcome.⁵

• A meta-analysis of studies looking at the role of ERCP in acute biliary pancreatitis has confirmed that early ERCP reduces both complications and mortality rates.

• Sphincter of Oddi dysfunction can lead to pancreatitis (usually in women following cholecystectomy) and responds to isolated biliary sphincterotomy.

Procedure

• ERCP is one of the most technically demanding and high-risk procedures performed by gastrointestinal endoscopists.

• ERCP is performed on an outpatient or inpatient basis.

• Patients have to fast overnight.

• Patients are usually sedated for the procedure (eg, using midazolam) and analgesia is also given.

• Antibiotics are usually given before the procedure for those patients with known or suspected obstruction in which complete relief of the obstruction is not anticipated or in patients receiving immunosuppression after liver transplantation.⁶

• Patients usually lie on their left side.

• The back of the throat is sprayed with a local anaesthetic.

• The endoscope is passed down through to the stomach and then to the duodenum (where the ducts of the pancreaticobiliary system open, called Vater's ampulla).

• Air may be pumped into the duodenum to allow better visualisation.

• Using a wire passed through the endoscope, contrast is injected through Vater's ampulla and X-rays obtained.

• These images will indicate areas of obstruction.

• Further intervention can be performed down the endoscope if necessary - eg, stone removal, stent insertion, biopsies.

Complications

• Pancreatitis - this is one of the most frequent post-ERCP complications. The incidence of this is around 20%.⁷ The majority of cases are mild but 10% of cases are moderate-to-severe and may lead to multi-organ failure and even death. The chances of pancreatitis post-ERCP can be reduced by avoiding excessive cannulation trauma and stent insertion - the latter being the most effective method.⁸ Stent insertion allows pancreatic secretions to pass freely.

• Post-ERCP pancreatitis rates are dependent on the type of ERCP performed.

• There is evidence that peri-operative indometacin or diclofenac helps to reduce the incidence of pancreatitis.⁹

• Infection may occur - although rates are low.

• Bleeding may occur - although severe haemorrhage is rare.

• Perforation of the duodenum with development of an acute abdomen.

• Failure of gallstone retrieval - may need to revert to open or more invasive procedures.

• Prolonged pancreatic stenting is associated with stent occlusion, pancreatic duct obstruction and pseudocyst formation.