A new classification of periampullary diverticulum: cannulation of papilla on the inner margins of the diverticulum (Type IIa) is more challenging

Abstract Background Periampullary diverticulum (PAD) may make the performance of endoscopic retrograde cholangiopancreatography (ERCP) in patients with choledocholithiasis more difficult and may increase complication rates. The present study evaluated the effects of PAD on first-time ERCP in patients with choledocholithiasis. Methods Outcomes were compared in patients with and without PAD and in those with four types of PAD: papilla located completely inside the diverticulum (type I), papilla located in the inner (type II a) and outer (type II b) margins of the diverticulum; and papilla located outside the diverticulum (type III). Parameters compared included cannulation time and rates of difficult cannulation, post-ERCP pancreatitis (PEP) and perforation. Results The median cannulation times in patients with types I, II a, II b, III PAD and in those without PAD were 2.0 min, 5.0 min, 0.67 min, 3.5 min, and 3.5 min, respectively, with difficult cannulation rates in these groups of 7.4%, 31.4%, 8.3%, 18.9%, and 23.2%, respectively. The rates of PEP in patients with and without PAD were 5.3% and 5.1%, respectively. Four patients with and one without PAD experienced perforation. Conclusions The division of PAD into four types may be more appropriate than the traditional division into three types. Cannulation of type I and II b PAD was easier than cannulation of patients without PAD, whereas cannulation of type II a PAD was more challenging. PAD may not increase the rates of PEP