The difference between the role of the hepatic vein and the portal vein is that the former drains blood from the liver into the inferior vena cava, while the latter drains blood from the abdominal organs into the liver.
1. The portal vein is one of the larger veins in the abdominal cavity and drains venous blood from organs other than the liver in the abdominal cavity, such as the intestines, spleen, pancreas, and gallbladder, as well as the pelvis and the lower esophagus.
The portal vein is composed of vessels such as the superior mesenteric vein, the inferior mesenteric vein, the splenic vein, the left gastric vein, the right gastric vein, the vein of the gallbladder, and the vein of the umbilical cord. Finally, the blood from the portal vein flows into the liver, and the blood passes through the hepatic sinusoids to form the hepatic vein. Therefore, the portal vein plays an important role in directing blood into the liver.
2. The hepatic veins are composed of sublobular veins between the lobules of the liver. The blood from the sublobular veins comes from the hepatic sinusoids. The sublobular veins form the left hepatic vein, the right hepatic vein and the middle hepatic vein, which converge to form the hepatic vein.
The hepatic veins exist primarily to transport filtered blood from the liver back to the inferior vena cava.
If a problem with the hepatic vein or portal vein is considered, consult a hepatobiliary surgeon at a regular hospital.