15. Radiology Case 3

Priyanka Dube¹ and Joshua K. Aalberg¹

(1)

Department of Emergency Medicine, Wexner Medical Center at The Ohio State University, Columbus, OH, USA

Priyanka Dube

Email: Priyanka.Dube@osumc.edu

Joshua K. Aalberg (Corresponding author)

Email: joshua.aalberg@osumc.edu

Keywords

PeripheryIntrahepatic portal veinsPortal venous gas Diagnostic cluesAcute bowel ischemiaPneumobilia

Indications for the Exam

A 71 y/o m presents with sudden-onset abdominal pain, diffusely tender without peritoneal signs.

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Radiographic Findings

Computed tomography (CT) axial image of the abdomen demonstrating portal venous gas.

Diagnosis

Mesenteric Ischemia.

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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