Collaterals in portal hypertension: anatomy and clinical relevance

Portal hypertension is a key pathophysiology of chronic liver diseases typified with cirrhosis or noncirrhotic portal hypertension. The development of collateral vessels is a characteristic feature of impaired portal hemodynamics. The paraumbilical vein (PUV), left gastric vein (LGV), posterior gastric vein (PGV), short gastric vein (SGV), splenorenal shunt (SRS), and inferior mesenteric vein (IMV) are major collaterals, and there are some rare collaterals. The degree and hemodynamics of collateral may affect the portal venous circulation and may compensate for the balance between inflow and outflow volume of the liver. Additionally, the development of collateral shows a relation with the liver function reserve and clinical manifestations such as esophageal varices (EV), gastric varices, rectal varices and the other ectopic varices, hepatic encephalopathy, and prognosis. Furthermore, there may be an interrelationship in the development between different collaterals, showing additional influences on the clinical presentations. Thus, the assessment of collaterals may enhance the understanding of the underlying pathophysiology of the condition of patients with portal hypertension. This review article concluded that each collateral has a specific function depending on the anatomy and hemodynamics and is linked with the relative clinical presentation in patients with portal hypertension. Imaging modalities may be essential for the detection, grading and evaluation of the role of collaterals and may help to understand the pathophysiology of the patient condition. Further investigation in a large-scale study would elucidate the basic and clinical significance of collaterals in patients with portal hypertension and may provide information on how to manage them to improve the prognosis as well as quality of life.