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Difficulty: MediumGastroenterology and Hepatology

A 74-year-old man is brought to the emergency department due to sudden-onset, severe abdominal pain that began 2 hours ago. He has a medical history of chronic obstructive pulmonary disease, heart failure with preserved ejection fraction, and paroxysmal atrial fibrillation. He recently stopped taking his prescribed apixaban. The patient reports nausea and one episode of vomiting. He also complains of mild shortness of breath. Temperature is 37.2∘C37.2^\circ\text{C} (99.0∘F99.0^\circ\text{F}), blood pressure is 150/90 mmHg150/90 \text{ mmHg}, pulse is 118 /min118\text{ /min} and irregularly irregular, and respirations are 22 /min22\text{ /min}. Pulse oximetry is 94%94\% on room air. Lung auscultation reveals scattered end-expiratory wheezes. The abdomen is soft and non-distended; there is mild, diffuse tenderness to palpation, but no rebound or guarding. Bowel sounds are decreased. Laboratory studies show:

Leukocyte count: 16,500/mm316,500/\text{mm}^3
Lactic acid: 3.8 mmol/L3.8 \text{ mmol/L}
Thyroid-stimulating hormone (TSH): 0.3μU/mL0.3 \mu\text{U/mL} (N: 0.4−4.0μU/mL0.4-4.0 \mu\text{U/mL})

Which of the following is the most appropriate next step in management?

  1. Computed tomography angiography of the abdomenAnswer
  2. B
    Intravenous furosemide and noninvasive positive pressure ventilation
  3. C
    Nasogastric tube decompression and serial abdominal examinations
  4. D
    Intravenous broad-spectrum antibiotics and clinical observation
  5. E
    Measurement of free thyroxine and triiodothyronine levels

Answer

The most appropriate next step in management is computed tomography angiography of the abdomen.
The patient's presentation is highly suspicious for acute mesenteric ischemia (AMI). The classic triad of AMI includes sudden onset of severe abdominal pain, pain out of proportion to physical exam findings (e.g., severe subjective pain but a relatively soft, non-tender abdomen), and a history of an embologenic disorder (e.g., atrial fibrillation). The elevated lactic acid and leukocytosis further suggest early bowel ischemia. In a hemodynamically stable patient without frank peritonitis, the most appropriate next step in management is to confirm the diagnosis with computed tomography angiography (CTA) of the abdomen. CTA can quickly and accurately identify the location of the vascular occlusion (most commonly the superior mesenteric artery), allowing for timely intervention.

Step-by-Step Solution

1
Analyze the clinical presentation.
The patient presents with sudden, severe abdominal pain that is out of proportion to the physical examination findings. He has an irregular pulse and a history of atrial fibrillation while off anticoagulation.
Identifying the classic 'pain out of proportion' in a patient with a high risk for arterial thromboembolism points directly to acute mesenteric ischemia.
2
Evaluate the objective laboratory data.
The laboratory results show leukocytosis and an elevated lactic acid level.
An elevated lactate in the setting of severe acute abdominal pain indicates tissue hypoperfusion and bowel ischemia, further increasing the clinical suspicion for a mesenteric vascular occlusion.
3
Determine the optimal diagnostic modality.
The patient is hemodynamically stable and does not have signs of frank peritonitis (no rebound or guarding). Therefore, imaging should be pursued before surgery.
Computed tomography angiography (CTA) of the abdomen is the gold standard and most appropriate next step to visualize the mesenteric vasculature, confirm the occlusion, and plan for potential endovascular or surgical revascularization.

Key Concept

Diagnosis of acute mesenteric ischemia
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Topics

Gastroenterology and Hepatology

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