Learning Radiology xray montage

Portal Venous Gas

General Considerations

  • Initially associated with bowel necrosis and death, portal venous gas is now being imaged in many benign conditions
  • Pathophysiologically, thought to be due to some combination of
    • Bowel distension
    • Damage to mucosa
    • Intra-abdominal sepsis

Causes of Portal Venous Gas


Umbilical vein catheters

Necrotizing enterocolitis (NEC)

Neonatal gastroenteritis

Erythroblastosis fetalis

Postoperative finding in corrective bowel surgery


Alterations of Bowel Wall

Ischemic bowel

Necrotic / ulcerated Colorectal carcinoma

Inflammatory bowel disease (Ulcerative Colitis)

Perforated peptic ulcer

Distension of bowel lumen

Bowel obstruction


Barium enema

Adynamic ileus


Acute gastric dilatation

Intra-abdominal Sepsis


Pelvic abscess

Cholecystitis and Cholangitis



Unknown Cause

Pneumatosis intestinalis

Corticosteroid use

Chronic obstructive lung disease


  • Frequently associated with gas in the bowel wall (pneumatosis intestinalis) when due to necrotic bowel

Clinical Findings

  • Will depend on the cause

Imaging Findings

  • Can be diagnosed on conventional radiography, CT or ultrasound
  • Branching, air-containing structures near or at the periphery of the liver
    • From centrifugal flow of blood in portal vein
  • More air accumulates in left portal vein as it is more anterior, but air is seen more easily on plain films in right lobe of liver
  • Thinner lucencies than air in branches of biliary tree (pneumobilia)
  • Air in biliary system is more central and branches are far fewer in number
  • Ultrasound shows bright, echogenic foci in the periphery of the liver with centrifugal flow

Differential Diagnosis

  • Air in the biliary tree (see above)


  • Surgery is usually performed for ischemic bowel disease especially for those with signs of perforation, sepsis or peritonitis


  • With bowel necrosis, mortality remains high (45-65%)
  • Without bowel necrosis, may spontaneously and quickly resolve without significant mortality

Portal Venous Gas. There is a small bowel obstruction with dilated loops of small bowel and gas
in the bowel wall (red circle). There are also black, branching structures at the periphery of the liver seen in the blue circles on the left and in the close-up on the right. This is the appearance of portal venous gas.
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Hepatic portal venous gas: transient radiographic finding associated with colchicine toxicity. Saksena, M; Harisinghani, M; Wittenberg, J and Mueller, P.  British Journal of Radiology (2003) 76, 835-837

Portal venous Gas. Radiopedia. D’Souza, D