segments. Number and course of liver veins is somewhat variable [ Figure 1] Portal vein Formed by the confluens of the splenic and superior mesenteric vein, the portal vein be sonographically displayed using or less dicular to the lower costal margin(orientation might be achieved referring from the right shoulder to the umbilicus), preferably in a left decubitus position and in variably deep inspiration Intrahepatically, the portal vein bifurcates into a main left and right branch. The first (right) portal vein branch splits into an anterior and into a posterior branch, which itself leads to the segments V-VIIl. The latter(left) main portal branch bifurcates into segments II and Ill and, additionally, into the left medial branches for segments (caudate lobe), IVa and Ivb[Figure 2] He atc arter The common hepatic artery has its source from the celiac axis, branching into the gastroduodenal artery and into the proper hepatic artery(arteria hepatica propria) Anatomical variations are frequent (in up to 50 %) e.g. the origin of the left proper hepatic artery out of the left gastric artery as well as the variable arterial supply of the liver by superior mesenteric artery branches. The hepatic artery runs with the portal vein, the right main arterial branch frequently meandering around the portal vein sonographically displayed in short segments medially (or less often laterally) of the portal vein. The normal and pathological flow patterns are described below in the Doppler chapt Bile ducts Bile ducts accompany the portal vein and hepatic artery branches from the liver hilum into the liver lobules, intrahepatically forming the ductus principalis dexter and the ductus principalis sinister, which join as common bile duct( CBD). The extrahepatic course of the CBd is cranially (pre-pancreatic)often ventral to the portal vein and caudally(intrapancreatic) more dorsolateral. The respective course of the hepatic artery is more variable [ Figure 4 Figure 4 Common bile duct(CBD). The CBD, and therefore, the liver hilum, is often best examined in a left lateral decubitus position using a subcostal approach in slight inspiration [video]. In the typical view CBd (in between markers), portal vein (PV), hepatic artery(HA), inferior vena cava(IVC) and right renal artery(RRa) (and sometimes also the aorta [ Aod can be seen; the papilla region(PAP)is indicated Distanz a 054cnsegments. Number and course of liver veins is somewhat variable [Figure 1]. Portal vein Formed by the confluens of the splenic and superior mesenteric vein, the portal vein can be sonographically displayed using scans more or less perpendicular to the lower costal margin (orientation might be achieved referring from the right shoulder to the umbilicus), preferably in a left decubitus position and in variably deep inspiration. Intrahepatically, the portal vein bifurcates into a main left and right branch. The first (right) portal vein branch splits into an anterior and into a posterior branch, which itself leads to the segments V – VIII. The latter (left) main portal branch bifurcates into segments II and III and, additionally, into the left medial branches for segments I (caudate lobe), IVa and Ivb [Figure 2]. Hepatic artery The common hepatic artery has its source from the celiac axis, branching into the gastroduodenal artery and into the proper hepatic artery (arteria hepatica propria). Anatomical variations are frequent (in up to 50 %), e.g. the origin of the left proper hepatic artery out of the left gastric artery as well as the variable arterial supply of the liver by superior mesenteric artery branches. The hepatic artery runs with the portal vein, the right main arterial branch frequently meandering around the portal vein sonographically displayed in short segments medially (or less often laterally) of the portal vein. The normal and pathological flow patterns are described below in the Doppler chapter. Bile ducts Bile ducts accompany the portal vein and hepatic artery branches from the liver hilum into the liver lobules, intrahepatically forming the ductus principalis dexter and the ductus principalis sinister, which join as common bile duct (CBD). The extrahepatic course of the CBD is cranially (pre-pancreatic) often ventral to the portal vein and caudally (intrapancreatic) more dorsolateral. The respective course of the hepatic artery is more variable [Figure 4]. Figure 4 Common bile duct (CBD). The CBD, and therefore, the liver hilum, is often best examined in a left lateral decubitus position using a subcostal approach in slight inspiration [video]. In the typical view CBD (in between markers), portal vein (PV), hepatic artery (HA), inferior vena cava (IVC) and right renal artery (RRA) (and sometimes also the aorta [AO]) can be seen; the papilla region (PAP) is indicated