525 A Review of Literature on Anatomical Variation of the Extrahepatic Biliary Tree Using Cadaveric Dissection and Imaging Modalities

Abstract

Abstract Aim The aim of this project was to examine world literature to establish the various types and frequencies of anatomical variants within the extrahepatic biliary tree, thereby contributing to the body of information available to anatomists, surgeons, and radiologists. Knowledge of the notoriously variable anatomy of the extrahepatic biliary tree is of greater importance than ever, given the increased occurrence and complexity of hepatobiliary and laparoscopic surgeries. Method A database search of MEDLINE, EMBASE and PubMed was conducted in June 2021 and returned 3440 articles, of which 29 were deemed eligible for inclusion. Results A rare malposition, the left-sided gallbladder, was observed in 0.04–0.60% across five studies. A normal cystic artery origin, that is, from the right hepatic artery was observed in 73.3–92% with variations being seen from the left hepatic artery (1–1.9%), gastroduodenal artery (1–7.5%) and the aberrant right hepatic artery (3–12.1%). It was also noted that in 3.6–32% of subjects the course of the cystic artery lay extraneous to Calot's triangle. Michels’ and Hiatt's classification systems were used to define the anatomical variations of the hepatic arteries: studies using Michels’ Type III reported a prevalence from 6.4–15%, Michels’ Type VI from 0.6–7% and Hiatt's Type III recorded an incidence ranging from 9.7–14.8%. Conclusion The most obvious finding to emerge from this project was the widely variable anatomy of the extrahepatic biliary tract and the contrasting reported data. Surgeons should therefore anticipate such complexities and adapt techniques to avoid biliary and arterial injuries and associated intra- and postoperative complications.