Optimal timing of precut sphincterotomy to prevent post-endoscopic retrograde cholangiopancreatography pancreatitis in difficult biliary cannulation: A retrospective study

INTRODUCTION

Endoscopic retrograde cholangiopancreatography (ERCP) is important for diagnosing and treating biliary diseases, and deep cannulation is the first and the most critical step in ERCP. Success directly affects the effectiveness of the procedure and patient prognosis. Although the success rate of deep biliary cannulation was reported to be 85%–95%,^{1, 2} approximately 5–10% of the attempts have been reported as difficult cannulation cases that required additional techniques to achieve biliary access. Various techniques such as precut sphincterotomy, pancreatic guidewire-assisted methods, and rendezvous techniques have been used to achieve deep biliary cannulation.³

However, the procedure is associated with severe complications, and post-ERCP pancreatitis (PEP) is one of the most common complications of ERCP. The incidence of PEP ranges from 2.1% to 10.2%,^4-6 and it can lead to severe outcomes. The risk factors for PEP can be categorized into patient- and procedure-related. Patient-related factors include younger age, female sex, and sphincter of Oddi dysfunction. Procedural factors include difficult bile duct cannulation and inadvertent pancreatic duct cannulation.^{6, 7} Precut sphincterotomy has also been reported as a risk factor for PEP.^8-11 However, some recent studies have suggested that early precut could reduce the incidence of PEP.^{12, 13} Our previous study also reported that precut was not a risk factor for PEP and that early precutting contributed to PEP prevention.¹⁴ Except for PEP, precut sphincterotomy also poses risks for other complications, such as bleeding and perforation. Therefore, their implementation must be carefully considered.

However, despite some reports stating that early precut has the potential for PEP prevention, there is no consensus on the optimal timing to start precut sphincterotomy. To resolve this issue, we conducted a retrospective study to determine the appropriate timing for initiating precut sphincterotomy in patients with difficult bile duct cannulation.

METHODS

This retrospective observational study adhered to the principles of the 1975 Declaration of Helsinki and was approved by the Institutional Research Ethics Committee (Approval No: 5984-01).

Patients

The patient selection process is summarized in Figure 1. This retrospective study was conducted at a single center, Kawasaki University General Medical Center, from April 2011 to December 2022. We enrolled 320 patients aged ≥20 years with normal gastrointestinal anatomy and Billroth I reconstruction with naïve papillae, who underwent precut sphincterotomy during their first ERCP attempt for biliary disease. The exclusion criteria were indications for a pancreatic procedure or pregnancy and not being allowed to provide informed consent. The included patients included 169 males (52.8%), with a mean age of 77.0 ± 13.7 years.

RESULTS

Optimal timing for precut papillotomy

An ROC analysis was performed to determine the optimal timing for precut sphincterotomy to prevent PEP. The area under the curve was 0.613, indicating moderate predictive accuracy (Figure 2). The optimal cutoff value for precut timing was 12.5 min, with a sensitivity of 61.5% and specificity of 63.9%. This threshold revealed the highest Youden Index of 0.255, which indicates balanced performance in predicting PEP risk.

DISCUSSION

This study revealed an association between the timing of precut sphincterotomy and the incidence of PEP in difficult cannulation cases. The results demonstrated that conversion to precut sphincterotomy within 12.5 min could significantly reduce the incidence rate of PEP compared with a delayed precut. Multivariate analysis identified delayed precut timing and absence of EPS as independent risk factors for PEP. These results reveal the clinical importance of appropriate timing for precut sphincterotomy and the efficacy of EPS in preventing PEP, even in precut cases.

The present study showed that 12.5 min was the optimal time for conversion to precut sphincterotomy, based on our ROC analysis. This result provides clinical criteria for the conversion to precut sphincterotomy in difficult cannulation cases. Although previous studies have suggested that early precut may effectively reduce the risk of PEP, the optimal timing for transitioning to precutting remains unclear. Early precut is widely defined as 5–20 min.^13-15 In this context, our study contributes to the operators by establishing a data-driven threshold of 12.5 min, which may serve as a practical guideline for clinical decisions. Early precutting prevents PEP by avoiding excessive manipulation of the major papilla. Prolonged cannulation attempts have been associated with an increased risk of PEP because repeated mechanical and chemical stimulation can lead to inflammation and pancreatic duct injury.^{16, 17}

The results of the ROC curve analysis in this study suggested that conversion to precut at 12.5 min provided an appropriate balance between avoiding delayed and premature precut sphincterotomies, which may expose patients to an increased risk of other adverse events. Converting to precut sphincterotomy at this threshold may reduce the risks associated with prolonged cannulation, while still allowing sufficient time for conventional cannulation attempts. However, early conversion to precut carries a risk of other complications. For example, if a precut is performed prematurely, patients who could have been successfully cannulated using conventional methods may undergo unnecessary precut sphincterotomy, which can lead to an increased risk of complications such as bleeding and perforation. Compared with standard cannulation techniques, precut sphincterotomy inherently involves greater technical difficulty and carries a higher risk of adverse events.¹⁸ Thus, precut should not be performed indiscriminately but at an optimal time that balances the benefits of reducing PEP risk with the risks of procedural complications. In our study, biliary cannulation was ultimately successful in 304/320 (95.0%) of cases, suggesting that early precut can be safely implemented in appropriate clinical settings without compromising procedural outcomes.

In terms of education, endoscopists must develop technical skills for conventional cannulation and clinical assessment to determine when conversion to precut sphincterotomy is appropriate. Overemphasis on early precut could lead to an awareness of indiscriminate precut sphincterotomy and an increase in severe complications. This approach can improve technical skills and clinical judgment, minimize avoidable complications, and ultimately improve patient safety and procedural outcomes. Furthermore, by adhering to an objective threshold such as 12.5 min, training programs can provide a structured approach to precut decision-making, reduce variability in practice, and improve standardization.

Second, EPS reduced the risk of PEP, even in precut sphincterotomy cases in the present study, and the use of EPS is widely recognized as an effective method for preventing PEP. Inadvertent pancreatic duct cannulation, contrast injection, or mechanical manipulation can lead to temporary obstruction of the duct, causing pancreatic fluid stasis and ductal hypertension, which contribute to the development of PEP.¹⁹ One of the main preventive mechanisms of EPS is decompression of pancreatic intraductal pressure by facilitating pancreatic juice drainage. Previous studies have demonstrated that EPS significantly lowers the incidence of PEP, particularly in high-risk cases, such as those involving multiple pancreatic duct cannulations or precut sphincterotomy.^{8, 19, 20} At our institution, EPS is commonly performed at the end of ERCP, particularly in patients who are difficult to cannulate. However, some reports have suggested that performing EPS before precut sphincterotomy may improve the success rate of bile duct cannulation.^{21, 22} One proposed mechanism is that securing the pancreatic duct with a stent may reduce the involuntary movement of the papilla, thereby allowing for a more controlled and effective precut sphincterotomy. This approach also has the potential to improve the success rate of bile duct cannulation in addition to preventing PEP. Thus, EPS is a valuable technique for preventing PEP in precut cases and potentially improving the success rate of precut sphincterotomy.

This study has certain limitations that should be noted when interpreting our findings. First, this study was retrospective and conducted at a single center. Second, the definition of precut timing and its applicability in various clinical settings may differ, thus necessitating external validation. Additionally, the decision to perform EPS was at the discretion of the endoscopist, which may have introduced variability. Finally, the study included a variety of endoscopists whose differences in technical skills may have affected the incidence of PEP. A limitation of this study is the differing strategies between trainees and experienced endoscopists. Trainees more often used alternative techniques before precut, contributing to longer procedures. Although operator experience was not an independent risk factor for PEP in multivariate analysis, this procedural difference may have influenced outcomes. Future studies should be stratified by operator experience.

In conclusion, the findings of this study suggest that conversion to precut sphincterotomy within 12.5 min and performing EPS are effective factors in reducing the incidence of PEP. These findings underscore the importance of timely decision-making during ERCP and highlight the need for proactive PEP prevention strategies in high-risk patients.

CONFLICT OF INTEREST STATEMENT

None.

ETHICS STATEMENT

The study protocol was approved by the Institutional Research Ethics Committee (Approval No: 5984-01). Animal studies were not applicable.

PATIENT CONSENT STATEMENT

This study was conducted with informed consent, in the form of an opt-out on the website.

CLINICAL TRIAL REGISTRATION

N/A.