Portal venous gas is the ominous sign in the clinical setting of mesenteric ischemia in adults or necrotizing enterocolitis. Mortality rates associated with portal venous system gas are 29%–43%. Other reported causes of portal venous system gas are pancreatitis, abdominal abscess, small bowel obstruction, large bowel obstruction, perforated gastric ulcer or carcinoma, diverticulitis, inflammatory bowel disease, abdominal trauma, ingestion of a caustic agent, enema administration, colonoscopy, gastrostomy tubes, and liver transplantation.

The imaging findings are

• Plain radiographs demonstrate linear at the periphery of the liver.
• On CT scans, air in the portal vein manifests as streaks of air that can reach the capsule at the periphery of the liver.
• Air has a propensity to accumulate in the the left portal vein due to its more ventral location.
• Pneumobilia is a differential consideration but gas with pneumobilia is more centrally located in the liver.

Patient #1

Patient #2: Patient presenting with portal venous gas and aortic dissection