Measurement of portal pressure: when, how, and why to do it.

Many of the clinical complications of cirrhosis are the direct consequences of the evaluation of portal venous pressure (PVP). The degree of portal hypertension has been shown to correlate with the severity of liver disease, both functionally and histologically. Direct measurement of PVP, however, is invasive and cannot be routinely performed. As a surrogate, the hepatic venous pressure gradient (HVPG) has been widely accepted as a measurement of PVP. The ease, accuracy, and safety of HVPG measurement has made it a valuable tool in the research arena and, increasingly, in clinical practice.