Mirizzi Syndrome With a Double Cystic Duct and a Single Gallbladder: A Case Report on a Rare Anatomical Variant and Surgical Challenge.

While various biliary anomalies have been documented in the literature, their occurrence in clinical practice is uncommon. Common anomalies encountered in practice include variations in cystic duct insertion (such as low or medial insertion), accessory hepatic ducts, and aberrant right hepatic ducts. Less commonly, clinicians may encounter double cystic ducts, duplicated gallbladders, or rare configurations associated with conditions like Mirizzi syndrome. Failure to identify key structures, such as the common hepatic duct (CHD), the common bile duct (CBD), the right hepatic duct (RHD), and the left hepatic duct (LHD), can result in serious intraoperative complications, most notably bile duct injury. Anomalies within Calot's triangle, in particular, increase this risk during laparoscopic cholecystectomy and underscore the importance of thorough anatomical knowledge and preoperative imaging. A 45-year-old female presented with symptomatic cholelithiasis and unremarkable laboratory results. She was scheduled for elective laparoscopic cholecystectomy under general anesthesia. During the dissection of Calot's triangle, an unexpected biliary anomaly was encountered: a double cystic duct in association with Mirizzi syndrome. Dissection was halted, and intraoperative cholangiography (IOC) was performed through the accessory duct. The cholangiogram confirmed a patent and anatomically intact CBD with no evidence of obstruction or injury. Surgery was then completed safely and without complications. A double cystic duct draining a single gallbladder is an extremely rare anomaly, with approximately only 20 cases described in the literature. These variations are typically not detected preoperatively and are most often discovered during surgery. In such cases, adjunct techniques like IOC or endoscopic retrograde cholangiopancreatography (ERCP) are essential to clarify anatomy and guide safe surgical intervention. Because preoperative imaging may fail to reveal biliary anomalies, surgeons must maintain a high index of suspicion and proceed with caution when encountering unclear anatomy during cholecystectomy. Selective use of IOC in suspicious cases may help prevent bile duct injury and associated complications, although its routine use remains a topic of ongoing debate in current surgical practice. Vigilance, anatomical awareness, and intraoperative flexibility are key to managing rare biliary variants and ensuring optimal patient outcomes.