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

BACKGROUND: Different types of periampullary diverticulum (PAD) may differentially affect the success of endoscopic retrograde cholangiopancreatography (ERCP) cannulation, but the clinical significance of the two current PAD classifications for cannulation is limited. AIM: To verify the clinical value of our newly proposed PAD classification. METHODS: A new PAD classification (Li-Tanaka classification) was proposed at our center. All PAD patients with native papillae who underwent ERCP from January 2012 to December 2017 were classified according to three classification systems, and the effects of various types of PAD on ERCP cannulation were compared. RESULTS: A total of 3564 patients with native papillae were enrolled, including 967 (27.13%) PAD patients and 2597 (72.87%) non-PAD patients. In the Li-Tanaka classification, type I PAD patients exhibited the highest difficult cannulation rate (23.1%, P = 0.01), and type II and IV patients had the highest cannulation success rates (99.4% in type II and 99.3% in type IV, P < 0.001). In a multivariable-adjusted logistic model, the overall successful cannulation rate in PAD patients was higher than that in non-PAD patients [odds ratio (OR) = 1.87, 95% confidence interval (CI): 1.04-3037, P = 0.037]. In addition, compared to the non-PAD group, the difficulty of cannulation in the type I PAD group according to the Li-Tanaka classification was greater (OR = 2.04, 95%CI: 1.13-3.68, P = 0.004), and the successful cannulation rate was lower (OR = 0.27, 95%CI: 0.11-0.66, P < 0.001), while it was higher in the type II PAD group (OR = 4.44, 95%CI: 1.61-12.29, P < 0.01). CONCLUSION: Among the three PAD classifications, the Li-Tanaka classification has an obvious clinical advantage for ERCP cannulation, and it is helpful for evaluating potentially difficult and successful cannulation cases among different types of PAD patients.