Currently the only existing test to measure portal pressure is to pass a pressure sensor through a vein in the neck, down into the liver. This is called the hepatic venous pressure gradient (HVPG) measurement. The HVPG measurement is disliked by patients because it is an invasive procedure. It is also expensive and not widely available. Hence, patients with cirrhosis need to have regular camera tests (endoscopies) to look for varices.