The aim of this study is to determine whether using a smaller wire results in a higher success rate at endoscopic retrograde cholangiopancreatography (ERCP), and lower incidence of adverse events

Cannulation of the bile duct is a prerequisite to successful therapeutic biliary endoscopy. Cannulation itself can carry substantial risk to the patient. Acute pancreatitis following ERCP can occur up to 5% of cases. The risk increases in patients with non dilated bile ducts, young age, known past history of pancreatitis and suspected sphincter of oddi dysfunction. During the procedure of ERCP, the number of pancreatograms also correlates with incidence of post ERCP pancreatitis. Hydrostatic pressure by contrast injection into the pancreatic duct may be the principal cause of pancreatitis. We performed a meta-analysis of randomized controlled trials that compared the technique of contrast guided to wire guide cannulation in achieving bile duct cannulation during ERCP and found that wire guide cannulation was better at the prevention of post ERCP pancreatitis. The use of a guide wire obviates the need for contrast injection. The current standard is the use of a 0.035" guidewire with a hydrophilic tip. We now postulate that the use of a 0.025" further reduces post-ERCP pancreatitis as a finer wire theoretically induces less trauma to the pancreatic orifice.

Inclusion Criteria:

• All patients referred for ERCP who have an intact naïve papilla are considered for inclusion

Exclusion Criteria:

• Age <18yrs
• Acute illness (hypotension: BP<90mmHg, hypoxia: O2 <95%, haemodynamic instability)
• Inability or refusal to give informed consent.
• Patients with previous sphincterotomy
• Pancreatic or ampullary cancer are excluded as post-ERCP pancreatitis (PEP) is very uncommon in these subgroups and tumour-related anatomical variation may alter cannulation technique.

(consider substratify results for this subgroup, but exclude if duodenal stenosis precludes an attempt on the papilla)

• Patients with surgically altered anatomy (Bilroth II gastrectomy and Roux en Y anastomosis) are excluded as cannulation technique is fundamentally different from that in normal anatomy.