Since its inception in 1968, endoscopic retrograde cholangiopancreatography (ERCP) has become an indispensable procedure for the management of pancreaticobiliary diseases [1]. Six years later, the first endoscopic sphincterotomies were completed by Kawai and Claussen and it is now used for indications including, but not limited to, stone removal from the common bile duct (CBD), management of papillary stenosis, or type 1 sphincter of Oddi (SOD) dysfunction and to facilitate the delivery of pancreaticobiliary therapy [2, 3]. The procedure, however, continues to result in significant morbidity in a small but not insignificant number of patients. Post-ERCP pancreatitis (PEP) is the major source of this, affecting between 5 and 7% of patients undergoing the procedure [2]. For 10% of patients who experience PEP, it can be severe and even fatal [3].

One risk factor of PEP is difficulty achieving biliary access. Factors include but are not limited to increased time to cannulation, increased number of cannulation attempts, and pancreatic duct cannulations. Although medical interventions such as intravenous volume expansion, pancreatic protease inhibitors, and NSAIDs have shown promise or even benefit, the risk of PEP persists [4–11]. Therefore, any intervention or technique that can minimize or even eliminate post-ERCP pancreatitis is highly desired.

The conventional technique involves the cannulation of the bile duct via the ampulla of Vater, followed by sphincter incision using electrocautery [12, 13]. This opens the distal end of the bile duct, allowing easier access for stents and removal of larger objects such as stones. It has been reported, however, that standard access techniques fail between 5 and 10% of the time [2]. If the standard method fails, then conventionally, precut techniques have been utilized as an alternative means of gaining biliary access. There are various precut techniques used to gain access to the common bile duct (CBD), which include needle-knife fistulotomy (NKF), needle-knife sphincterotomy (NKS), and trans-pancreatic precut sphincterotomy (TPS) [14, 15].

Needle-knife fistulotomy involves identifying the intra-duodenal segment of the bile duct and uses a needle-knife to incise directly into the bile duct. The fistula is away from the native orifice of the papilla. NKS involves using a needle knife to cut starting at the native orifice and incising upwards to expose the bile duct opening. A TPS involves incising the pancreatic sphincter, which lies adjacent to the biliary sphincter (within the native orifice), to expose the biliary opening.

Numerous studies have demonstrated that adverse event rates are comparable between methods when precut sphincterotomy is conducted by an expert endoscopist [16] and that moving to precut techniques earlier in the procedure can be associated with fewer adverse events [17–19]. With respect to which of the three techniques to employ, the NKF theoretically offers the lowest risk of pancreatitis as the incision is performed directly into the intra-duodenal segment of the bile duct, minimizing any contact or thermal damage to the pancreatic duct. This theory is supported by the results in the series by Jin et al., who observed a 0% incidence of pancreatitis using the NKF method as the initial technique for cannulation in high-risk patients [20]. Additionally, our recent prospective study of 50 patients demonstrated the safety and feasibility of the NKF precut technique as a primary means of gaining biliary access [21]. Without a control group, however, our trial could not compare the current results to the standard cannulation technique.

The next logical step then is to conduct a randomized controlled trial (RCT) to compare the efficacy and safety of initial NKF to the standard cannulation in a non-selective patient population undergoing ERCP. The objective of this study is to add to the literature of ERCP that assesses NKF as the initial method of gaining biliary access. The primary outcome of the study will be the incidence of PEP. Our hypothesis is that NKF will have a lower PEP rate than standard cannulation.