CT of the abdomen  – 

There is a single abnormal vessel connecting the portal vasculature with the systemic circulation. The dilated shunt vessel emerges from the portal vein level with the junction of the right gastric vein, bypasses the liver crossing in a long loop to the left side and caudally and enters the caudal vena cava level with the cranial pole of the right kidney from the left side. The extrahepatic portal vein is uneven and small in diameter cranial to the shunt emergence. The hepatic artery presents compensatory enlargement. The intrahepatic branching of the portal vein is within normal limits. Second order portal veins could be seen within the hepatic parenchyma. Microhepatica is noted. The gallbladder is moderately distended, the gallbladder wall is mildly thickened. The pancreas presents mild generalized enlargement.  The spleen is enlarged which likely is a function of congestion. There is multifocal post contrast heterogeneity due to differential enhancement of the red and white pulpa in the early post contrast series. There is mild bilateral renomegaly with a medullary rim sign.