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Difficulty: HardGastroenterology and Hepatology

A 7474-year-old woman is brought to the emergency department from a skilled nursing facility due to sudden-onset, severe abdominal pain and altered mental status. Staff report that she had several episodes of bloody diarrhea earlier in the day. Her medical history includes hypertension, type 2 diabetes mellitus, and paroxysmal atrial fibrillation for which she frequently misses her doses of apixaban. Her temperature is 38.4∘C38.4^\circ\text{C} (101.1∘F101.1^\circ\text{F}), blood pressure is 82/50 mmHg82/50\text{ mmHg}, heart rate is 128/min128/\text{min} and irregular, and respiratory rate is 24/min24/\text{min}. On physical examination, she appears lethargic. The abdomen is rigid with diffuse involuntary guarding and severe rebound tenderness. Bowel sounds are absent.

Laboratory results:
Leukocytes: 22,500/μL22,500/\mu\text{L}
Hemoglobin: 11.2 g/dL11.2\text{ g/dL}
Platelets: 210,000/μL210,000/\mu\text{L}
Lactic acid: 8.4 mmol/L8.4\text{ mmol/L}
Bicarbonate: 12 mEq/L12\text{ mEq/L}

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

  1. A
    Computed tomography angiography of the abdomen and pelvis
  2. B
    Administration of intravenous sodium bicarbonate
  3. Immediate exploratory laparotomyAnswer
  4. D
    Intravenous fluid resuscitation and nasogastric tube decompression
  5. E
    Empiric intravenous ciprofloxacin and metronidazole pending stool culture results

Answer

Immediate exploratory laparotomy
The correct intervention is immediate exploratory laparotomy. This patient's presentation of sudden-onset, severe abdominal pain in the setting of unanticoagulated atrial fibrillation is classic for acute mesenteric ischemia. The subsequent development of a rigid abdomen, rebound tenderness, severe lactic acidosis, and hypotension indicates transmural bowel infarction and peritonitis. In any patient with an acute surgical abdomen and hemodynamic instability, emergent laparotomy is required to resect the necrotic bowel. Delaying surgery for imaging or relying on conservative measures is associated with near-universal mortality.

Step-by-Step Solution

1
Analyze the patient's risk factors and initial presentation.
The patient has a history of atrial fibrillation without consistent anticoagulation, presenting with sudden, severe abdominal pain out of proportion to early exam findings, and bloody diarrhea.
These historical and clinical features are highly suggestive of acute mesenteric ischemia secondary to an arterial embolus, most commonly lodging in the superior mesenteric artery.
2
Evaluate the physical examination and laboratory findings for complications.
The patient now demonstrates a rigid abdomen, rebound tenderness, hypotension (82/50 mmHg82/50\text{ mmHg}), significant leukocytosis, and severe lactic acidosis (8.4 mmol/L8.4\text{ mmol/L}).
These advanced signs indicate that the initial ischemia has rapidly progressed to transmural bowel infarction, resulting in perforation, generalized peritonitis, and septic/hypovolemic shock.
3
Determine the most appropriate management based on the patient's clinical stability.
The next best step is an emergent exploratory laparotomy.
While computed tomography (CT) angiography is the standard diagnostic test for early mesenteric ischemia, patients exhibiting frank peritonitis or hemodynamic instability must bypass imaging and proceed directly to the operating room for resection of the necrotic bowel.

Key Concept

Patients with acute mesenteric ischemia who develop signs of peritonitis (e.g., rigid abdomen, rebound tenderness) or hemodynamic instability require emergent exploratory laparotomy without delay for diagnostic imaging.
Estimated Time:1m 30s
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Topics

Gastroenterology and Hepatology

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