What is the next step in managing a 71-year-old male with a history of atrial fibrillation (AF) and colon cancer presenting with sudden onset of severe abdominal pain, tachycardia, and hypotension?

Management of Sudden Onset Abdominal Pain in a 71-Year-Old with Atrial Fibrillation and Colon Cancer

CT scan with contrast is the most appropriate next step for this patient with atrial fibrillation and sudden onset severe abdominal pain, as it will rapidly identify potential mesenteric ischemia requiring urgent intervention.

Clinical Assessment and Rationale

The patient's presentation raises immediate concern for mesenteric ischemia based on several key factors:

• High-risk profile: 71-year-old with atrial fibrillation (major risk factor for embolic events)
• Acute presentation: Sudden onset of severe abdominal pain
• Vital signs: Tachycardia (HR 132) and borderline hypotension (BP 100/70)
• Physical exam: Moderate abdominal pain on palpation with hyperactive bowel sounds

These findings are highly concerning for acute mesenteric ischemia (AMI), particularly embolic occlusion of the superior mesenteric artery (SMA), which is the most common cause of AMI 1.

Diagnostic Algorithm

1. Immediate imaging: CT angiography (CTA) of the abdomen and pelvis

   • Triple-phase study (non-contrast, arterial, and portal venous phases)
   • Will identify vascular occlusion, bowel ischemia, and exclude other diagnoses 1
   • Can detect filling defects in proximal SMA consistent with embolus

2. Laboratory studies (to be drawn concurrently):

   • CBC, electrolytes, serum creatinine
   • Inflammatory markers (C-reactive protein, procalcitonin, lactate) 1
   • These should not delay imaging but provide additional diagnostic information

Why CT with Contrast is Superior to Other Options

• Diagnostic accuracy: CTA is the gold standard for diagnosing mesenteric ischemia with high sensitivity and specificity
• Comprehensive assessment: Evaluates both vascular status and bowel viability
• Treatment planning: Identifies the underlying cause and guides intervention approach 1

Management Based on CT Findings

If CT shows SMA embolus without bowel infarction:

• Immediate anticoagulation
• Urgent angiography with aspiration embolectomy or transcatheter thrombolysis 1

If CT shows SMA embolus with signs of bowel infarction:

• Immediate surgical revascularization
• Exploratory laparotomy for bowel assessment and possible resection 1

Important Clinical Considerations

• Time-critical condition: Mortality approaches 60% if diagnosis and intervention are delayed 1
• Atrial fibrillation: Major risk factor for embolic events; this patient's history significantly increases the likelihood of mesenteric ischemia
• Colon cancer history: May complicate management but does not change the immediate diagnostic approach

Common Pitfalls to Avoid

1. Delaying imaging: Waiting for laboratory results before obtaining CT can lead to irreversible bowel ischemia
2. Underestimating severity: The physical exam may be misleadingly benign in elderly patients with catastrophic conditions 2
3. Focusing only on pain management: While analgesia is important, identifying and treating the underlying cause is paramount

The patient's presentation with sudden abdominal pain, tachycardia, and history of atrial fibrillation demands urgent evaluation with CT angiography to rule out mesenteric ischemia before irreversible bowel damage occurs.