Clinical significance of different periampullary diverticulum classifications for endoscopic retrograde cholangiopancreatography cannulation

Figure 2 Li-Tanaka classification of periampullary diverticulum. Type I: The papilla is located inside the diverticulum and not adjacent to the margin; type II: The papilla is located in the margin of the diverticulum (type IIa: Inside of the margin; type IIb: Outside of the margin, < 1 cm); type III: The papilla is located outside the margin, ≥ 1 cm; type IV: The papilla is located in the margin of the diverticulum, ≥ 2 diverticula (type IVa: The papilla is located outside the margins of at least one diverticulum, < 1 cm; type IVb: The papilla is located outside the margins of all the diverticula, ≥ 1 cm).