Needle knife fistulotomy in flat and diverticular papillae – is it time for redemption?

European Society of Gastrointestinal Endoscopy (ESGE) recommends needle-knife fistulotomy (NKF) as the preferred precut technique in cases when standard cannulation techniques fail. Despite scarce scientific evidence, flat and diverticular papillae are thought not to be ideal for NKF, as they are associated with poor outcomes. The present study aimed to determine the outcomes of the use of NKF in relation to flat and intradiverticular papillae.This prospective multicenter study enrolled consecutive patients, evidencing naïve flat (group A, n = 49) or diverticular papilla (group B, n = 28), who underwent NKF after failure of standard cannulation techniques. Diverticular morphology was subdivided into intradiverticular (group B1, n = 14) and diverticular border papillae (group B2, n = 14), using a previously validated endoscopic classification of the major papilla. The success of biliary cannulation at initial endoscopic retrograde cholangiopancreatography (ERCP), overall biliary cannulation, overall cannulation time, and the rate of adverse events were assessed in the study.The initial cannulation rates were 93.9%, 64.3% and 71.4% for group A, B1, and B2, respectively (P = 0.005); overall cannulation rates after a second ERCP were 98.0%, 92.9% and 85.7%, respectively (P = 0.134). Adverse events occurred in 11.7% of patients, with post-ERCP pancreatitis (PEP) being the most common adverse event (10.4%). Although there was a trend towards a higher incidence of PEP in flat papillae, univariate and multivariate analyses did not show any significant relationship between pancreatitis and trainee involvement, papillary morphology, nor overall cannulation time.Although flat papillae are associated with high success rates of biliary cannulation using NKF, the rate of PEP is not negligible. NKF is feasible in diverticular papillae, but it is associated with a modest success rate in the initial ERCP.