Participants in this study will be undergoing a procedure called an endoscopic retrograde cholangiopancreatography (ERCP). This procedure is most commonly performed to help treat conditions affecting specific areas of the digestive system called the pancreas and bile ducts.

Patients will consent to allow the study physician to access these areas of the digestive system by making a cut using a technique called a needle-knife fistulotomy. If the physician is unable to gain access through this method, they will make the cut using a technique called a sphincterotomy.

The ERCP procedure enables doctors to examine the regions of the digestive system called the pancreas and bile ducts. After sedating a patient, a bendable tube with a light (called an endoscope), is inserted through the mouth and into the digestive system. Within the digestive system, the doctor is able to identify the opening to where the gallbladder drains into the small bowel called the ampulla. Using the endoscope, a small plastic tube is then placed in the opening and dye (also called contrast material) is injected bile duct (where bile leaves the liver from). X-ray pictures can then be taken to provide further information to the doctor.

Sometimes it is necessary to make a cut to enlarge the opening to allow easier removal of stones from the bile duct or to place plastic tubes (stents) in the bile duct. To make this cut, there are two different approaches that the doctor can take:

1. The standard way of making the cut is referred to as a "sphincterotomy". Using this method, a heated metal wire cuts the opening to the bile duct after a wire has been passed into it.
2. The second way of making the cut is referred to as a "pre-cut". There are various types of "pre-cut" techniques; the technique being evaluated in this study is called the "needle knife fistulotomy". When using this technique, the doctor makes a cut directly into the bile duct using a tiny knife called a "needle knife".

Currently, there is not a standard that tells doctors what cutting technique to use. The decision is entirely up to the individual doctor.

Patients that participate in this study give their permission to allow the study doctor to use the "needle knife fistulotomy" cutting technique first to gain access to the bile ducts. If the study doctor is unable to gain access through this method, then they will use the standard sphincterotomy technique.

The purpose of this study, called a feasibility study, is to determine if the needle-knife fistulotomy is at least as safe and effective as the standard access technique, if not safer.

If it can be shown that the needle-knife fistulotomy is safer and/or more effective, then it could change the way that doctors conduct this procedure in Canada and the rest of the world.

Inclusion Criteria:

1. Patients, ages > 18, with an intact sphincter undergoing ERCP by at Kingston Health Sciences Center for therapeutic purposes who can provide informed consent. This includes patients who have confirmed choledocholithiasis on imaging and those who have a high suspicion of it based on imaging and lab values. Patients with and without a high suspicion for cholangitis will be eligible for the study. Other indications include: type 1 sphincter of Oddi dysfunction, gallstone pancreatitis or other benign pancreaticobiliary duct diseases including strictures, primary sclerosing cholangitis and Mirizzi's syndrome. Furthermore, patients with suspected diagnosis of biliary leak following cholecystectomy will also be considered for enrollment in this study.
2. Ability to read and understand the English language

Exclusion criteria:

1. Bleeding disorder (Von Willebrand disorder, platelet count <100 000, or INR >1.5)
2. Therapeutic level anticoagulation with low molecular weight heparin (LMWH), warfarin, or a direct-acting oral anticoagulant (DOAC)
3. Prior biliary sphincterotomy
4. Altered upper GI tract anatomy (e.g. prior gastric bypass surgery such as Roux-en-Y or Billroth 2 gastrojejunostomy)
5. Evidence of Malignant infiltration of the ampulla or peri-ampullary area.
6. Inability to identify intra-duodenal portion of the bile duct, including deep peri-ampullary diverticulum.