Portal venous gas

Portal venous gas is the accumulation of gas in the portal vein and its branches. It needs to be distinguished from pneumobilia, although this is usually not too problematic when associated findings are taken into account along with the pattern of gas (i.e. peripheral in portal venous gas, central in pneumobilia).

Pathology

Etiology

Although traditionally considered a harbinger of death, portal venous gas is increasingly recognized in a variety of conditions, many of which do not carry as high mortality or morbidity risks.

Causes of portal venous gas are best divided according to the age of the patient:

• child

  • umbilical vein catheterization

  • necrotizing enterocolitis (NEC)

  • neonatal gastroenteritis

  • erythroblastosis fetalis

  • postoperative finding in corrective bowel surgery

• adult

  • alterations of the bowel wall

    • ischemic bowel (usually mural gas as well as mesenteric gas: mortality of 75-90%, but gas is not an independent predictor)

    • necrotic/ulcerated colorectal carcinoma (CRC)

    • inflammatory bowel disease (IBD)

    • perforated peptic ulcer

  • bowel luminal distention

    • iatrogenic gastric and bowel dilatation (e.g. upper and lower endoscopic procedures, enemas)

    • paralytic ileus or mechanical bowel obstruction

    • acute gastric dilatation ⁴

    • barotrauma

  • intra-abdominal sepsis

    • diverticulitis

    • infectious colitis

    • pelvic abscess

    • cholecystitis/cholangitis

    • appendicitis

    • hemorrhagic pancreatitis ¹

  • unknown mechanism

    • pneumatosis intestinalis

    • chronic obstructive pulmonary disease (COPD)

    • corticosteroid usage

    • diabetes mellitus ¹

    • diarrhea ¹

    • cardiopulmonary resuscitation ⁸

Radiographic features

Plain radiograph

Branching lucencies projected in the liver or vessels coursing towards the liver.

Ultrasound

Gas in the portal veins usually manifests as echogenic mobile foci in the lumen of the portal vein. Doppler ultrasound will demonstrate sharp spikes on both sides of the basal line on the Doppler spectral display ⁷.

CT

Similar to x-ray features, portal venous gas manifests on CT as branching gaseous foci of low density in the liver, portal vein and its tributaries. The vessel-gas interface may cause streak artifact. Typically, the gas in the liver is peripheral which helps differentiate it from more central gas due to pneumobilia. 

History and etymology

The first description of hepatic portal venous gas as a radiological observation was in 1955 by Wolfe and Evens ⁹.

See also

• abnormal intra-abdominal gas