Cirrhosis causes increased pressure within the liver and changes in the circulation leading to the development of varicose veins in the gullet and stomach called 'varices'. Varices bleed easily, leading to emergency situations that can be life threatening. However, if the increased pressure within the liver (portal pressure) is detected early, then treatment can prevent variceal bleeding. The only test we have to predict prognosis and treatment success in someone with cirrhosis is by measuring the portal pressure.