Examkin

Question

Difficulty: MediumPhysical Examination Findings

A 74-year-old woman is brought to the emergency department by her son due to the sudden onset of agonizing abdominal pain that started two hours ago. She has a medical history of hypertension, hyperlipidemia, and paroxysmal atrial fibrillation. She stopped taking her prescribed apixaban three weeks ago due to financial difficulties. Her temperature is 37.1∘C37.1^\circ\text{C} (98.8∘F98.8^\circ\text{F}), blood pressure is 155/90 mmHg155/90 \text{ mmHg}, heart rate is 118/min118/\text{min} and irregularly irregular, and respiratory rate is 22/min22/\text{min}. She appears in extreme distress, continuously writhing and unable to find a comfortable position on the stretcher. Abdominal examination reveals a flat, non-distended contour. Bowel sounds are hypoactive. The abdomen is completely soft and exhibits only mild, diffuse tenderness to deep palpation. There is absolutely no guarding, rigidity, rebound tenderness, or palpable organomegaly. Digital rectal examination shows normal sphincter tone and brown, Guaiac-negative stool. Laboratory studies demonstrate a leukocyte count of 16,500/mm316,500/\text{mm}^3 and a serum lactate level of 3.2 mmol/L3.2 \text{ mmol/L} (normal: 0.5−2.2 mmol/L0.5-2.2 \text{ mmol/L}). Which of the following is the most likely diagnosis given the striking disparity between this patient's subjective symptoms and her objective physical examination findings?

  1. Embolic occlusion of the superior mesenteric arteryAnswer
  2. B
    Spontaneous perforation of a duodenal ulcer
  3. C
    Acute inflammation of a colonic diverticulum
  4. D
    Rupture of an abdominal aortic aneurysm
  5. E
    Transient systemic hypoperfusion secondary to tachyarrhythmia

Answer

Embolic occlusion of the superior mesenteric artery
The patient's clinical presentation is classic for acute mesenteric ischemia (AMI), which in this case is likely caused by an embolic occlusion of the superior mesenteric artery due to her un-anticoagulated atrial fibrillation. The quintessential physical examination hallmark of early AMI is severe, agonizing abdominal pain that is entirely out of proportion to the objective abdominal exam findings. Because the visceral peritoneum is poorly innervated and the parietal peritoneum is not yet inflamed, the abdomen typically remains soft and non-tender (or only mildly tender) without guarding, rigidity, or rebound tenderness. The elevated leukocyte count and serum lactate reflect early bowel ischemia, necessitating emergent intervention.

Step-by-Step Solution

1
Analyze the patient's risk factors and history.
The patient has paroxysmal atrial fibrillation and recently discontinued anticoagulation, placing her at very high risk for arterial thromboembolism.
Identifying the pathophysiologic risk factors helps narrow the differential diagnosis for sudden-onset conditions.
2
Evaluate the physical examination findings against the subjective symptoms.
The patient has agonizing, writhing abdominal pain, but her abdomen is soft, non-distended, and lacks peritoneal signs (no guarding, rigidity, or rebound).
This specific discrepancy—pain out of proportion to the physical exam—is the classic clinical hallmark of a specific vascular catastrophe.
3
Interpret the laboratory findings in the context of the physical examination.
The elevated leukocyte count and rising serum lactate indicate early tissue ischemia and necrosis, corroborating a severe underlying ischemic event despite the benign outer abdominal exam.
Lactate elevation in the setting of acute abdominal pain without peritonitis strongly points to bowel ischemia.
4
Synthesize all findings to arrive at the most likely diagnosis.
The combination of atrial fibrillation, sudden severe pain, a benign physical examination, and elevated lactate establishes the diagnosis of acute mesenteric ischemia.
No other diagnosis perfectly accounts for the vascular risk factors, the laboratory abnormalities, and the hallmark physical examination discrepancy.

Key Concept

The hallmark physical examination finding of acute mesenteric ischemia is severe, agonizing abdominal pain that is strikingly out of proportion to a relatively benign, soft, and non-peritonitic abdominal exam.

Alternative Method

While physical examination is the initial key to suspecting this diagnosis, the definitive next step in management would be CT angiography of the abdomen to visualize the arterial occlusion.
Estimated Time:1m 30s
Rate this question

Topics

Physical Examination Findings

More questions from this topic