Portal venous gas, also known as hepaticportalvenousgas (HPG), refers to the presence of gas in the portal vein, its intrahepatic branches, and the vessels of the gastrointestinal tract at all levels, often transiently, not as an independent disease, but as a sign that usually accompanies gastrointestinal disease, most commonly in the form of intestinal ischemia and necrosis. The sign can also occur in non-digestive pathologies such as sepsis and abdominal infections, and in about 15% of cases PVG is idiopathic. PVG can be caused by the synergistic effect of one or more factors: 1) destructive changes in the mucosa of the intestinal wall; 2) increased pressure in the alimentary canal; 3) infection with gas-producing bacteria. Pathogenesis: It is generally believed that there are two pathways: 1. Increased pressure in the intestinal canal, edema and necrosis of the intestinal mucosal layer, destruction of the mucosal barrier, and gas in the intestinal lumen entering the small veins of the intestinal wall through the mucosal breaks and refluxing to the portal vein via the mesenteric vessels. 2.Infection of gas-producing bacteria in the intestine and abdominal cavity spreads to the intestinal mucosa or small vein, and direct infection of gas-producing bacteria in the vein causes gas accumulation in the portal vein.