How to indirectly estimate portal venous pressure to confirm the diagnosis of portal hypertension?
Catheterization of a hepatic vein is performed via jugular or femoral vein access. The catheter is advanced until it obstructs a small hepatic vein branch, or a balloon occlusion catheter is inflated within the hepatic vein to obstruct its outflow. The wedged hepatic vein pressure is actually a measure of sinusoidal pressure but allows for a reasonable indirect estimate of portal venous pressure. A corrected sinusoidal pressure measurement is obtained by subtracting the measured mean free hepatic venous pressure from the mean wedged hepatic venous pressure. Corrected sinusoidal pressure measurements ≤5 mm Hg are considered normal. Measurements of 6 to 10 mm Hg are compatible with mild portal hypertension, and measurements >10 mm Hg are compatible with more severe portal hypertension.