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.