Clinical investigation of the cystic duct variation based on the anatomy of the hepatic vasculature.

Anatomical variation of the cystic duct (CD) is rare but can result in misunderstanding of the CD anatomy during laparoscopic cholecystectomy, potentially leading to bile duct injury. Therefore, the precise preoperative identification of CD variation is important. However, preoperative imaging analyses of the biliary system are not always possible or sufficient. We therefore investigated CD variations based on the anatomy of the hepatic vasculature. This study enrolled 480 patients who underwent imaging before hepatobiliary pancreatic surgery. We assessed the variation of the CD and hepatic vasculature and evaluated the correlations among these variations. A variant CD anatomy was identified in 12 cases (2.5%) as CD draining into the right hepatic bile duct (BD) in 4 cases and into the right posterior BD in 8 cases. CD variation was significantly more common in cases with portal vein (PV) and BD variation than in those without the variation. We developed a scoring system based on the presence of PV and BD variations that showed good discriminatory power for identification of CD variants. Cases with a variant CD anatomy were more likely to exhibit variant PV and BD anatomies than cases with a normal CD anatomy. These findings will be useful for the preoperative identification of CD variants.