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15. Radiology Case 3
Keywords
PeripheryIntrahepatic portal veinsPortal venous gas Diagnostic cluesAcute bowel ischemiaPneumobiliaIndications for the Exam
Radiographic Findings
Computed tomography (CT) axial image of the abdomen demonstrating portal venous gas.
Diagnosis
Learning Points
Priming Questions
What is the pathophysiology that causes portal venous gas and pneumobilia?
How do you differentiate these on imaging?
What pathologies are associated with each?
Introduction/Background
The above case is concerning for acute bowel ischemia. On this CT, one can identify gas (dark on CT) within the periphery of the intrahepatic portal veins, indicating portal venous gas [1].
A common pitfall is understanding the differences between portal venous gas and pneumobilia. Understanding these diagnostic clues is necessary as they indicate different and serious pathologies. The goal of this section is to educate the reader on these differences to aid in prompt recognition and diagnosis.
Pathophysiology/Mechanism
Sign | Description | Pathophysiology |
|---|---|---|
Portal venous gas | Gas within the portal veins that typically extends to the periphery just beneath the liver capsule | Gas (formed from iatrogenic, gas-forming organisms, and/or increased intraluminal pressure) enters the portal veins through venous/lymphatic drainage of the intestinal wall |
Pneumatosis | Gas within the bowel wall [2] | Gas buildup within the bowel wall secondary to ischemia, increased intraluminal pressure, or bowel infarction. May also be from gas-forming organisms |
Pneumobilia | Gas in the hepatobiliary tree that is located more centrally | Most commonly, this finding indicates a connection between the biliary tract and the gastrointestinal tract, either iatrogenically or pathologically via a fistula formation. Less commonly, infection of the biliary system with a gas-forming organism can cause pneumobilia |
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