Other regions where portal and caval systems interconnect include: where the liver is in direct contact with the diaphragm (the bare area of the liver); where the wall of the gastrointestinal tract is in direct contact with the posterior abdominal wall (retroperitoneal areas of the large and small intestine); and the posterior surface of the pancreas (much of the pancreas is secondarily retroperitoneal).
Blockage of the hepatic portal vein or of vascular channels in the liver