Arterial ring encircling the bile duct with coexisting anomalous liver irrigation.

Analysis of the arterial system of the liver in a 64-year-old male cadaver revealed an anomaly of the branching of the proper hepatic artery. The right branch of the hepatic artery was missing, replaced by two segmental arteries, so that a 'trifurcation' occurred, consisting of two segmental arteries, anterior segmental and posterior segmental, and the left branch of the hepatic artery. These segmental arteries formed an arterial ring around the common hepatic duct, completely encircling it. A single cystic artery unusually originated from the posterior segmental artery. An extremely rare anatomical variation of the dorsal liver segment irrigation proves the fact that anatomical anomalies are usually multiple. The arterial blood supply for the dorsal liver segment is through four separate vessels ('quadruple type'), two originating from the left branch of the hepatic artery and two from the posterior segmental artery. These four arteries presented numerous anastomotic bridges among themselves.