Study of Forceps Cannulation During ERCP

Overview

A difficult cannulation has been identified as one of the high risk factors for developing post-ERCP pancreatitis (PEP). The accessibility and morphology of the papilla influence the level of cannulation difficulty. The use of a forceps to assist in the cannulation is a demonstrated effective technique for cannulating papillae that are difficult to access. Thus, the objective of our study is to determine whether a forceps assisted cannulation leads to less difficult cannulation during ERCP. Because difficult cannulation is associated with increased risk of PEP, our study investigates whether the forceps assisted cannulation also reduces the incidence of PEP as a secondary outcome. Eligible patients who have consented will either be randomized to cannulation with forceps or cannulation with no forceps.

Endoscopic retrograde cholangiopancreatography (ERCP), an invasive procedure that combines endoscopy and x-ray to treat issues with the bile and pancreatic ducts, carries a two to ten percent risk of causing post-ERCP pancreatitis (PEP) \[1\]. Because acute pancreatitis is a devastating inflammatory condition that leads to extensive morbidity and mortality, efforts to reduce the risk of PEP in patients undergoing ERCP would enhance patient outcomes and would decrease the economic burden in treating PEP nationwide \[2-4\]. A difficult cannulation has been identified as one of the high risk factors for developing PEP \[5\]. A study performed by Scandinavian Association for Digestive Endoscopy (SADE) determined that cannulations with five or more attempts, a duration of five minutes or longer, or two or more unintended pancreatic duct (PD) wire passages significantly increased one's risk for PEP \[6\]. Thus, SADE defined a difficult cannulation as any cannulation with at least one of the following conditions: five or more attempts, five or more minutes, or two or more unintended PD wire passages \[6\]. This classification of a difficult cannulation has been adopted and standardized by the European Society of Gastrointestinal Endoscopy \[7\]. Because no current guidelines defining a difficult cannulation exist from the American College of Gastroenterology or American Gastroenterological Association, the European Society of Gastrointestinal Endoscopy (ESGE) guidelines as gathered from the SADE study are the worldwide standardized definition of difficult cannulation. Difficult cannulations have been reported to occur at a frequency of 42 percent for all ERCP exams \[8\]. The morphology and accessibility of the papilla influence the level of difficulty. Some studies have indicated that different macroscopic appearances of the papilla result in varying cannulation difficulty levels. Based on a study gauging intraobserver and interobserver agreement to the macroscopic appearance of different papillae, papillae are categorized as: Type 1, normal appearing; Type 2, small; Type 3, protruding or pendulous; and Type 4, ridged or creased \[9\]. Haraldsson et al. found that Type 2 and Type 3 papillae were more difficult to cannulate \[8\]. Regardless of papilla type, the involvement of a trainee (a GI fellow) resulted in more difficult cannulations \[8\]. In addition, the presence of redundant tissue, such as periampullary diverticula-which occurs in up to 20 percent of patients undergoing ERCP-results in more challenging cannulations \[10\]. The use of a forceps to assist in the cannulation is a demonstrated effective technique for cannulating papillae that are difficult to access \[10-12\]. The forceps clears the redundant tissue to enable access to the papilla, as well as stabilizes the ampullary position to permit an easier cannulation \[10\]. Currently, no randomized controlled trials that detail to what extent a forceps facilitates cannulation exist. Thus, our study aims to determine whether a forceps assisted cannulation reduces the incidence of difficult cannulations and consequently PEP. The primary outcome is difficult cannulation after randomization. A difficult cannulation will be defined as any cannulation that results in any of the following: 5 or more minutes, 5 or more cannulation attempts, or 2 or more unintentional pancreatic wire passages. The secondary outcome is PEP. Acute pancreatitis according to the Atlanta guidelines, is at least two of the following: abdominal pain consistent with pancreatitis, lipase or amylase greater than 3 times the upper limit of normal, radiographic evidence of pancreatitis on cross sectional imaging \[13\]. The study intervention is the use of a forceps during the cannulation. Eligible patients who have consented will either be randomized to forceps assisted cannulation or no forceps used during cannulation. The forceps is an FDA approved instrument and does not put the patient at any higher risk for any adverse event. SOCCER plans to enroll 152 patients. All patients undergoing ERCP at Dartmouth-Hitchcock endoscopy will be approached and consented for this study. Medical records will be reviewed to see if they meet inclusion/exclusion criteria. Patients will be consented day of the procedure. We received an approved HIPAA Authorization Waiver because access to a patient's chart will be required to determine inclusion/exclusion criteria. Consent will be performed in the endoscopy pre-op area. During the standard of care ERCP, the patients will be randomized intraoperatively to either cannulation with forceps and cannulation with no forceps. Written informed consent will be reviewed and signed before any study related procedures are performed. Please note that the primary outcome refers to a difficult cannulation AFTER randomization when the secondary inclusion criteria has been met. For example, if the secondary inclusion criteria met is difficult cannulation, then the primary outcome would be if from that point forward there were a difficult cannulation. As such, a total cannulation time of 10 minutes would enable the patient to be eligible (the first 5 minutes means the cannulation is difficult) and would mean the subject met the primary outcome (the second 5 minutes means cannulation after randomization is difficult). However, a total cannulation time of 8 minutes means the patient is eligible for the study (first 5 minutes means the cannulation is difficult) but did not meet the primary outcome (after randomization, the cannulation was not difficult because it was only 3 minutes). In a sense, the "difficult cannulation clock" is reset after randomization. If the secondary inclusion criteria met instead is papilla location or type, then the patient is randomized immediately before the cannulation and the difficult cannulation clock starts then. Measurement of difficult cannulation starts immediately after randomization upon the doctor's first cannulation attempt following randomization. Randomization will occur in block format. Randomization assignments will be placed in sealed manila envelopes that will be opened at the time of randomization. Manila envelopes will be kept with the study coordinator. After consent, data will be collected before, during, and after the procedure. The primary outcome will be measured during the procedure, whereas the secondary outcome will be determined during the 5 day follow up call. The study coordinator, GI fellow, or attending physician will call the patient 5 days (+/- 2 days) post-procedure to determine whether the patient developed PEP. Though it is preferred to contact the patient, other methods (chart review, emergency contact, outside records) are acceptable for determining the secondary outcome.