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Difficulty: MediumGastrointestinal and Abdominal Surgery

A 65-year-old woman presents to the emergency department complaining of sudden, excruciating abdominal pain that began 90 minutes ago. She has a history of rheumatic heart disease, mitral stenosis, and paroxysmal atrial fibrillation for which she takes a beta-blocker. She admits to frequently missing her oral anticoagulant doses. On physical examination, her temperature is 37.2°C (99.0°F), blood pressure is 142/85 mmHg, pulse is 118/min and irregularly irregular, and respirations are 18/min. Her abdomen is soft, non-distended, and non-rigid. Palpation elicits mild, diffuse tenderness without guarding or rebound. Bowel sounds are decreased. Laboratory studies show a leukocyte count of 14,500/mm³ and serum lactate of 4.2 mmol/L. Which of the following is the most appropriate next step in management?

  1. Computed tomography angiography of the abdomenAnswer
  2. B
    Exploratory laparotomy
  3. C
    Nasogastric tube decompression, intravenous fluids, and observation
  4. D
    Right upper quadrant ultrasonography
  5. E
    Transthoracic echocardiography

Answer

Computed tomography angiography of the abdomen
The patient's presentation of sudden-onset, severe abdominal pain that is out of proportion to the benign physical examination, particularly in the setting of atrial fibrillation and an elevated serum lactate, is highly characteristic of acute mesenteric ischemia (AMI). The most common cause is an arterial embolus to the superior mesenteric artery. In a hemodynamically stable patient who lacks peritoneal signs (e.g., no rigidity or rebound tenderness), the most appropriate next step is computed tomography (CT) angiography of the abdomen. This imaging modality rapidly identifies the vascular occlusion and helps assess for signs of advanced ischemia or early bowel infarction, which dictates the subsequent surgical or endovascular intervention.

Step-by-Step Solution

1
Analyze the patient's risk factors.
The patient has a history of mitral stenosis and atrial fibrillation with poor medication adherence.
Identifies a high risk for systemic arterial embolization.
2
Evaluate the clinical presentation.
Sudden onset of severe abdominal pain that is out of proportion to the relatively benign physical examination (soft, non-rigid abdomen) combined with an elevated lactate level.
This is the classic triad for acute mesenteric ischemia, specifically an embolus to the superior mesenteric artery.
3
Determine the hemodynamic status and presence of peritonitis.
The patient is hemodynamically stable with normal blood pressure, and there are no signs of peritonitis (no rebound or guarding).
Differentiates whether the patient can safely undergo imaging or requires emergent surgical exploration.
4
Select the appropriate next diagnostic step.
Computed tomography angiography of the abdomen is selected.
It is the rapid, non-invasive gold standard test to confirm vascular occlusion in a stable patient without peritonitis.

Key Concept

Diagnosis of Acute Mesenteric Ischemia
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Topics

Gastrointestinal and Abdominal Surgery

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