Anatomic variations of the extrahepatic biliary tree. A monocentric study and review of the literature

Introduction: The study of the anatomy of the extrahepatic bile ducts has demonstrated the existence of a significant number of variants which can be explained by hepato-biliary embryology. A good knowledge of this anatomy is essential for the interpretation of radiological examinations, and for a good practice of hepato-biliary and pancreatic surgery. Several imaging methods are used to study the anatomy of the bile ducts, including classical cholangiography, which is still practiced and very useful. Aim: To study the modal anatomy (the most frequent) and the anatomical variants of the extrahepatic bile ducts through the interpretation of postoperative cholangiograms and to examine their implication on the surgical practice. Methods: This is a monocentric, retrospective observational study. It concerned any patient who underwent hepato-biliary or pancreatic surgery at the Department of General and Digestive Surgery of Farhat Hached University Hospital of Sousse between 2007 and 2016, and who received postoperative cholangiography. A data form was fulfilled for each patient. Results: Out of a total population of 293 patients, we identified 158 patients (53.9%) with anatomic variants of the extrahepatic bile ducts. The common bile duct was modally implanted in the second duodenum in 96.2% of cholangiographies and in the genu inferius in 3.8% of cases. The main pancreatic duct had a V-shaped implantation in 87.1% of cholangiograms, a U-shaped implantation in 4.2% of cases and a Y-shaped implantation in 7.1% of cases. The common bile duct had a modal aspect in 71.3% of cholangiograms, with 28.7% of anatomic variants, organized in 4 models. The cystic duct had a modal presentation in 80.9% of cases, and we recorded 6 other branching models (19.1% of cases). No significant difference was observed between the presence of anatomic variants on the one hand, and age, sex, conversion rate, intraoperative incidents, postoperative complications, postoperative hospital stay and overall hospital stay on the other hand. Conclusion: Conventional cholangiography constitutes a more or less precise tool for detecting these anatomic variants and is therefore very useful in the practice of hepato-biliary surgery even after the advent of new techniques in this field. However, it also requires a more extensive and in-depth knowledge of these anatomic variants, which nevertheless remain quite frequent, and represent a source of surgical difficulties. Key-words: Anatomy, Anatomic variations, Extrahepatic bile ducts, Surgery.