Aberrant right posterior hepatic duct opening into the cystic duct: a very rarely seen biliary anatomic variation.

Embryological development of the biliary tract is a complex process and may result in various anatomic variations. The classification commonly used in the literature for the assessment of biliary tract variations, was developed by Huang et al. [1]. This classification has five types (●" Table1) based on the point of opening of the right posterior branch [2]. In this case study of a patient who was undergoing endoscopic retrograde cholangiopancreatography (ERCP) to treat choledocholithiasis, we present a right posterior hepatic duct opening into the cystic duct (Huang type A5), which is a biliary anatomic variation that is very rarely seen. A 64-year-old woman presented to our hospital with complaints of abdominal pain and jaundice. On transabdominal ultrasonography, the intrahepatic biliary ducts were bilaterally dilated, the common bile duct was measured to be 12mm at its widest portion, and a stone with posterior shadowing was observed at its distal portion. On ERCP, the common bile duct and intrahepatic biliary ducts were observed to be dilated and small stones were seen inside the lumen. Furthermore, the cystic canal was observed to open into the right posterior hepatic duct (●" Fig.1). The stones were removedwith a stone extraction balloon by performing an endoscopic sphincterotomy. Cholecystectomy was planned, and the patient was then transferred to the surgery department with a note warning the surgeon about this rare biliary variation. Lack of previous knowledge on the type of biliary anatomical variation may lead to bile leakage, bilioma, biliary fistula, biliary peritonitis, or abscess and cholangitis complications as a result of iatrogenic traumas during hepatobiliary surgery [2–5]. These complications can be more common, particularly in right hepatic duct variations that drain into the cystic duct [1,2,4]. Consequently, knowledge and evaluation of the anatomic variations of the biliary tracts are important before surgery and interventions.