Classification of the cystic duct patterns and endoscopic transpapillary cannulation of the gallbladder to prevent post-ERCP cholecystitis

BACKGROUND: Endoscopic transpapillary cannulation of the gallbladder is useful but challenging. This study aimed to investigate cystic duct anatomy patterns, which may guide cystic duct cannulation. METHODS: A total of 226 patients who underwent endoscopic transpapillary cannulation of the gallbladder were analyzed retrospectively. RESULTS: According to the cystic duct take-off, 226 cystic duct patterns were divided into 3 patterns: Type I (193, 85.4%), located on the right and angled up; Type II (7, 3.1%), located on the right and angled down; and Type III (26, 11.5%), located on the left and angled up. Type I was further divided into three subtypes: Line type, S type (S1, not surrounding the common bile duct; S2, surrounding the common bile duct), and α type (α1, forward α; α2, reverse α). Types I and III cystic ducts were easier to be cannulated with a higher success rate (85.1 and 86.4%, respectively) compared with Type II cystic duct (75%) despite no statistically significant difference. The reasons for the failure of gallbladder cannulation included invisible cyst duct take-off, severe cyst duct stenosis, impacted stones in cyst duct or neck of the gallbladder, sharply angled cyst duct, and markedly dilated cyst duct with the tortuous valves of Heister. CONCLUSION: Classification of cystic duct patterns was helpful in guiding endoscopic transpapillary gallbladder cannulation.