Portal hypertension is an increase in pressure within the portal vein, the vessel that carries blood from the intestines and the spleen to the liver. It occurs when either there is a blockage or malformation of the vein itself, or when cirrhosis or another form of liver disease blocks the flow of blood through the liver.
All of the blood coming from the intestines passes through the liver through a large vein called the portal vein. The liver is the only organ to receive the majority of its blood supply through a vein instead of an artery. Typically, the pressure in veins is much lower than the blood pressure in arteries. The low pressure in the portal vein allows blood to percolate slowly through the liver and gives liver cells the time they need to do their work.
Increased pressure in the portal vein causes pressure in other veins to increase as well. Rising pressure can force blood to back up into the splenic vein, causing the spleen to swell.
As the body senses the increased portal vein pressure, it tries to compensate by growing new veins that bypass the liver. These new veins, calledPortal Hypertension Liver Disease – Boston Children’s Hospital
varices, tend to be full of twists and turns. They are much weaker than normal veins and can bleed easily. Varices tend to grow around the esophagus, spleen, stomach and colon.