Cystic duct anatomical variations and the risk of choledocholithiasis: a systematic review and meta-analysis

Background: Cystic duct anatomy is clinically significant for surgery and stone formation, yet the literature lacks a systematic analysis linking variations to common bile duct stones. This study investigated their prevalence and risk for choledocholithiasis. Methods: We systematically searched PubMed, Embase, Web of Science and Scopus for studies on cystic duct morphology and choledocholithiasis. Pooled prevalence, risk ratios (RRs), and odds ratios were calculated using R; heterogeneity and bias were assessed via AQUA and Peter's tests. Results: High (17.2%) and posterior (13.8%) insertions were most prevalent. Factors significantly associated with choledocholithiasis included a long cystic duct (RR 1.50, 95% confidence interval [CI] 1.18-1.90), low insertion (RR 1.46, 95%CI 1.06-1.76), spiral course (RR 1.41, 95%CI 1.06-1.86), and posterior insertion (RR 1.32, 95%CI 1.07-1.60). Lithiasis patients exhibited wider cysto-choledochal angles (47.1° vs. 40.8°). Geographic analysis revealed a high prevalence of low insertion in African populations (21.8%) and spiral ducts in East Asians. Conclusions: Cystic duct variations significantly increase susceptibility to choledocholithiasis and pose surgical challenges. As these complex anatomical courses and configurations are often missed, preoperative imaging is essential. Early identification enables safer surgical planning, reduces biliary injury risk, and can guide tailored strategies to prevent lithiasis in high-risk groups.