ABSTRACT
Pathologic increase in portal pressure can be caused by increased resistance to blood flow at the level of the portal vein (pre-hepatic), hepatic sinusoids (hepatic) or hepatovenous outflow (post-hepatic). This results in recruitment and dilatation of tiny portosystemic collateral pathways, diverting portal venous blood flow to low pressure systemic veins. Based on the location of the causative factor of portal venous resistance, different collateral pathways and shunts may develop, resulting in unique syndromes of portal hypertension and in-turn requiring unique treatment options. Knowledge of the common and less-common portosystemic collateral pathways have important implication for clinicians and interventionalists. The objective of this pictorial review is to illustrate the various collateral pathways using diagrammatic and conventional non-invasive and invasive radiologic examples. Additionally, we will briefly address minimally invasive interventional techniques used to treat the sequelae of portal hypertension.