A Cautionary Tale of Anatomical Variations of the Extrahepatic Biliary System and Their Implications for Surgical Procedures: A Systematic Literature Review

Background The hepatobiliary system has the most associated anatomical variations in the body and they are a direct reflection of the complexity of its embryological development. The anatomical pattern commonly described as ‘normal’ occurs only in 57–72% of the population. The objective of the study is to review the English Language published literature on the prevalence of the anatomical extra-hepatic biliary system variations and their potential implications for surgical and endoscopic procedures. This will assist both practicing and trainee surgeons in preventing biliary tract injuries while operating in this area. Methodology A comprehensive literature search was conducted using the PICO framework across SCOPUS, PubMed, MEDLINE, and Cochrane databases. Study characteristics and relevant data were collated. The prevalence of the most clinically important anatomical variations is presented. Results Seventy studies, encompassing 17,207 subjects, were included: 27 studies (9,738 subjects) on cystic duct variations, 17 studies (2,633 subjects) on gallbladder variations, and 26 studies (4,836 subjects) on cystic artery variations. Notable findings include low insertion (11.2%), medial insertion (9.8%), and parallel course (7.4%) of the cystic duct, Hartmann’s pouch in 12.2% of gallbladders, and the cystic artery originating from the right hepatic artery in 83.6% or other sources in 16.4%. Moynihan’s hump of the right hepatic artery was found in 1.8%. Conclusion These variations are frequent and surgically relevant. Understanding them is critical to avoiding complications. Employing the critical view of safety in laparoscopic cholecystectomy ensures proper visualization of anatomical structures, reducing the risk of injury.