The aims of this study are to compare the needle knife fistulotomy (NKF) technique versus the partial ampullary endoscopic mucosal resection (PA-EMR) technique in patients with difficult biliary cannulation and to assess the incidence rate of complications between these cannulation methods.

Cannulation success with standard techniques reported to be around 95% even in expert hands and despite all efforts, it can be challenging that needs an alternate intervention.

NKF is recommended as the initial technique for pre-cutting because the rate of post-ERCP pancreatitis (PEP) is significantly low but there is an ongoing debate about limiting its use in certain types of papillae with a long intra-mural segment

Indeed the shape of the papillae influences the success of bile duct cannulation and the choice of the pre-cutting technique. Type-2 and Type-3 papillae are more difficult to cannulate than Type-1. NKF can be performed as the initial technique for pre-cutting in protruded Type-2 and Type-3 papillae but it has some limitations.

First of all, the incision can be erratic because it is performed without a guidewire and uncontrolled. This can cause a tattered mucosa as the incision progress and the papillae lose anatomic contours. Some amount of bleeding may also unavoidably occur and the field of view further impaired. If the initial incision line is incorrect and additional incision is needed, more crumpled and deformed papillae with irregular margins may be encountered. These undesired results are frequently experienced and prevent a clean-cut, thus further complicate the cannulation. Even perforation can occur.

Recently the investigators described a novel technique, PA-EMR, for difficult biliary cannulation in patients with protruded Type-2, Type-3, and shar-pei papilla. The investigators hypothesized that with this new technique cannulation success will be higher, procedure time will be shorter and the adverse events will be lower versus NKF technique.

Inclusion Criteria:

• Patient who submitted a written informed consent for this trial, and aged between 18-90 years old
• Patient who have naïve papilla (no previous procedure was performed at ampulla)
• Patient who is suspected to have a biliary obstruction or biliary disease
• Patient who is needed to have endoscopic retrograde cholangiopancreatography for treatment of biliary obstruction
• Patient who have risks of post-endoscopic retrograde cholangiopancreatography p

Exclusion Criteria:

• Patient who is pregnant

• Patient with mental retardation

• Patient allergic to contrast agents

• Patient who received sphincterotomy or pancreatobiliary operation previously

• Patient who have ampulla of Vater cancer

• Patient who have difficulty for the approach to ampulla due to abdominal surgery including stomach cancer with Billroth II anastomosis

• Patient who have pancreatic diseases as bellow (at least one more);

  • acute pancreatitis within 30days before enrollment
  • idiopathic acute recurrent pancreatitis
  • pancreas divisum
  • obstructive chronic pancreatitis
  • pancreatic cancer

• Patients with Type-1, non-protruding Type-2 and Type-4 papilla