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Difficulty: MediumInterpreting Imaging Results

A 74-year-old man is brought to the emergency department due to a 4-hour history of agonizing, diffuse abdominal pain. He recently survived an anterior myocardial infarction and has a known left ventricular apical aneurysm. Vital signs show a temperature of 37.2°C (99.0°F), blood pressure of 160/95 mmHg, pulse of 115/min, and respirations of 22/min. On physical examination, the patient is writhing in discomfort, but his abdomen is soft, non-distended, and exhibits only mild diffuse tenderness to deep palpation with no rebound or guarding. A contrast-enhanced computed tomography (CT) scan of the abdomen reveals an abrupt cutoff in a major mesenteric vessel and diminished mural enhancement of several distal jejunal loops. The radiologist also notes distinct, linear, branching radiolucencies located strictly within the substance of the bowel wall. Which of the following is the most accurate interpretation of these linear radiolucencies?

  1. Pneumatosis intestinalis, indicating established or impending transmural bowel infarctionAnswer
  2. B
    Free intraperitoneal air, indicating an overt transmural gastrointestinal perforation
  3. C
    Portal venous gas, indicating a primary severe ascending hepatobiliary infection
  4. D
    Intraluminal air-fluid interfaces, indicating an established mechanical small bowel obstruction
  5. E
    Submucosal fat deposition, indicating chronic mural inflammation from inflammatory bowel disease

Answer

Pneumatosis intestinalis, indicating established or impending transmural bowel infarction
The correct interpretation of linear, branching radiolucencies strictly within the bowel wall is pneumatosis intestinalis. In a patient with classic signs of acute mesenteric ischemia (pain out of proportion to exam, high-risk embolic source, and CT evidence of arterial occlusion), this finding demonstrates that the ischemia has progressed to severe transmural necrosis. The necrotic breakdown of the mucosal barrier allows intraluminal gas to dissect into the submucosal and subserosal planes. It is a harbinger of imminent perforation and necessitates emergency surgical exploration.

Step-by-Step Solution

1
Analyze the clinical presentation.
The patient has sudden-onset abdominal pain that is entirely out of proportion to his benign physical exam. Combined with a recent anterior myocardial infarction and apical aneurysm (high risk for thromboembolism), this strongly suggests acute embolic mesenteric ischemia.
Establishing the pre-test probability guides the interpretation of complex or subtle imaging findings.
2
Evaluate the primary CT findings.
The arterial cutoff and diminished mural enhancement confirm compromised intestinal perfusion.
Confirms the diagnosis of vascular occlusion leading to ischemia.
3
Interpret the specific radiographic sign in question.
The distinct, linear radiolucencies described as being strictly within the substance of the bowel wall represent gas dissecting into the mural layers.
This specific imaging pattern describes pneumatosis intestinalis.
4
Synthesize the finding with the underlying pathology.
In the setting of acute ischemia, pneumatosis intestinalis signifies that the mucosal barrier has broken down due to necrosis, allowing intraluminal bacteria and gas to invade the wall.
Determines the clinical severity, signaling impending perforation and the urgent need for surgical intervention.

Key Concept

Radiographic identification and clinical significance of pneumatosis intestinalis in acute mesenteric ischemia.
Estimated Time:1m 30s
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Topics

Interpreting Imaging Results

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