Endoscopic retrograde cholangiopancreatography and how to avoid them

With the progress made by endoscopic ultrasound (EUS) and magnetic resonance cholangiopancreatography (MRCP), ERCP is now strictly limited to use in therapeutic situations, such as stone extraction and stenting. In fact, ERCP is not a good procedure to diagnose stones in the common bile duct, with only 70% sensitivity, whereas EUS has a sensitivity of 95%. Furthermore, the morbidity rate after ERCP is far from low and it is now clearly recommended that EUS and/or MRCP be used for diagnosis and then ERCP performed only when treatment is needed.¹ The only remaining indication for diagnostic ERCP is tissue sampling at biliary stenosis, but even in this case stenting is frequently required to treat the stenosis and prevent cholangitis.

Endoscopic cannulation of the bile duct, with associated sphincterotomy, can induce acute pancreatitis in approximately 5%, bleeding in 4.5%, and perforation in 0.1% of cases.² The main risk factors for pancreatitis are well known. For example, young women who have Sphincter of Oddi dysfunction or those who have repeated cannulation or opacification of the main pancreatic duct are at greater risk of developing acute pancreatitis following ERCP.³ Pancreatitis is generally mild and self-limiting and conservative management is sufficient in more than 90% of cases.⁴ Bleeding and perforation complications occur in about 1% of cases ⁵ and are mostly managed conservatively using endoscopic haemostasis, clipping or stenting. However, even more than for other endoscopic examinations, it is essential to give a clear explanation to the patient of the benefits and risks of the procedure, and this must be recorded in the patient medical file in order to limit the potential for medicolegal issues in case an adverse event occurs. 

The ESGE (European Society of Gastrointestinal Endoscopy) does not recommend endoscopic papillary balloon dilation as an alternative to sphincterotomy in routine ERCP due to the risk of pancreatitis.⁶ However, endoscopic papillary balloon dilation may be advantageous in selected patients, such as those who are taking anticoagulant drugs without acute possible reversion and who need an emergency ERCP (i.e. due to septic shock).⁷ If this technique is used, the duration of dilation should be longer than 1 minute to get good sphincter dilation.⁴

Except in cases of hilar stenosis, because of the risk of cholangitis (see below), complete mapping of the intrahepatic biliary tree is advised to detect additional diseases, such as intrahepatic stones or stenosis, which could explain the occurrence of recurrent cholangitis. Opacification should be conducted with a certain pressure, using, for example, an extraction balloon to avoid contrast leakage in the duodenum. Different pictures taken from different axes are needed to understand bile duct insertion and to avoid structure superposition. All the segmental intrahepatic bile ducts should be visible and analysed one by one. In fact, MRI (MRCP, magnetic resonance cholangiopancreatography) is also effective and combining MRI with ERCP is another option to reduce the opacification of the bile tract and exposure of the patient to X-rays.¹¹

One of the major, classic mistakes to be avoided when performing ERCP is to begin the procedure in cases of hilar stenosis without first mapping the obstructed bile ducts with MRCP.^11,12 Opacification of occluded bile ducts may lead to cholangitis if this duct cannot be drained with a stent.⁴ Prior ERCP, precise mapping and a precise drainage strategy are needed.¹² Which technique should be used (ERCP, percutaneous drainage or immediate surgical resection)? Which duct should be drained? How many ducts should be drained? Having a strategy allows the catheterization and injection of only those areas that have to be drained. 

The differential diagnosis between cholangitis and cholangiocarcinoma is challenging and may require histological analysis of several brushing or biopsy samples.¹³ Inserting one or more metal stents in case of primary sclerosing cholangitis or in case of neoplastic disease that is reversible by chemotherapy is a mistake because stent removal is usually impossible. Patients will present with stent obstruction and repeated cholangitis and are at risk of developing secondary sclerosing cholangitis and/or cholestatic cirrhosis.^14,15 Furthermore, placement of a noncovered metallic stent can prevent further biliary sampling. The expert recommendation is usually, therefore, to insert plastic stents until the diagnosis is obtained or to perform a percutaneous drainage with a silicone tube.

ECRP can be very effective at stopping a biliary post-surgical leakage.¹⁶ Depending the location and the associated biliary lesions, different options (e.g. papillotomy alone, nasobiliary drainage, stenting, stone removal) have to be used. The first step is nevertheless to demonstrate the leakage by ERCP and the mistake is to perform any therapeutic manoeuvre without such a demonstration, especially when the leakage is from the intrahepatic bile ducts following a partial hepatectomy.^16,17 Indeed, leakage can arise from intrahepatic biliary ducts isolated by the liver resection from the rest of the biliary tree. Prior to ERCP, MRCP is, therefore, essential to verify whether any sector is excluded or not and to localize the bile duct defect. Following ERCP, sphincterotomy is therefore not justified in the first instance while the leakage is not clearly seen, because it presents an additional risk of acute pancreatitis without any benefit for the patient.³ When a leakage is suspected but not demonstrated at the time of the first contrast injection, it is suggested to inject contrast medium under pressure, for example with an occluding balloon (expert recommendation). 

Biliary stenosis following a difficult cholecystectomy is usually located at the level of the common hepatic duct. The stenosis is frequently complete and difficult to pass even with a hydrophilic guidewire. A frequent mistake is to mix up the cystic duct stump and the occluded common hepatic duct and to repeatedly push the guidewire into the cystic duct stump. The two channels superimpose on fluoroscopy, but there are two possible solutions. First, to always think that the cystic duct stump can superimpose and mimic the stenotic common hepatic duct. Second, to change the radiological exposure in order to separate both ducts on imaging. 

Mirizzi syndrome type I is a common bile duct compression that is caused by a stone impacted at the neck of the gallbladder or at the cystic duct.^18,19 The compression induces obstructive jaundice and its diagnosis and treatment are challenging. It has been reported that there is an association with gallbladder cancer in one third of Mirizzi cases and Mirizzi syndrome can also masquerade as cholangiocarcinoma. Thickening of the gallbladder or the cystic duct wall is not specific enough to rule out or confirm the presence of associated cholangiocarcinoma. Management of Mirizzi syndrome is usually a combination of endoscopy and surgery and repeated attempts to treat Mirizzi syndrome endoscopically should be avoided in patients at low surgical risk.^19,20