Difficult biliary cannulation in ERCP procedures with or without trainee involvement: a comparison study.

Aims 5-5-1 criteria have been proposed by the European Society of Gastrointestinal Endoscopy to define difficult ERCP cannulation. However, the criteria may be inappropriate for cannulation procedures with trainee involvement. Here we aimed to develop difficult cannulation criteria in trainee involved cannulation. Methods Patients undergoing biliary cannulation with (trainee group) or without trainee involvement (non-trainee group) were eligible. The procedures which might be too easy (e.g. fistula) or too difficult (e.g. altered anatomy) was excluded. The primary outcome was difficult cannulation, which was defined as the values of cannulation time, attempts, or inadvertent PD cannulation exceeding 75% percentile of each variable. Propensity score matching analysis was used. Results After PSM, there were 1596 patients in each group. The trainee group had longer median cannulation time [7.5 (2.2-15.3) min vs. 2.0 (0.6-5.2) min], more median attempts [5 (2-10) vs. 2 (1-4)] and median inadvertent PD cannulation [0 (0-2) vs. 0 (0-1)] compared with the non-trainee group (all p<0.001). 15-10-2 and 5-5-1 difficult cannulation criteria determined by exceeding 75% percentile of cannulation variables were proposed for trainee involved cannulation and were nearly confirmed for non-trainee involved cannulation, respectively. The proportion of difficult cannulation was 35.5% 95%CI [33.2%, 37.9%] and 31.8% 95%CI [29.5%, 34.2%] respectively (OR 1.18 95%CI [1.02-1.37]). The incidence of PEP (7.8% 95%CI [5.7%, 10.3%] vs. 9.8% 95%CI [7.4%, 12.8%]) in difficult patients were comparable. Conclusion By using 75% percentiles of cannulation-related variables as cutoff values, we proposed that 15-10-2 difficult cannulation criteria could be appropriate in trainee involved cannulation.