This
note describes the formation, tributaries and major site for the portocaval
anastomosis (also called portosystemic anastomosis or portal-systemic anastomosis).
Portal Vein
The
portal vein is the vein of the gut that drains blood from the abdominal part of
the gastrointestinal tract from the lower third of esophagus to halfway down
the anal canal including spleen, pancreas and gall bladder.
Formation
It
is about 2 inches long and formed by the union of superior mesenteric vein and
splenic vein behind the neck of the pancreas. It ascends to the right behind
the first part of the duodenum and enters the free margin of the lesser
omentum. Entering through the porta hepatis, it divides into right and left
terminal branches which further break up into sinusoids. The blood from the
sinusoids is collected by hepatic veins that join the inferior vena cava.