General Surgery · Year 3 · from General Surgery

Case 3: Acute Mesenteric Ischemia

Patient Demographics

  • Age: 72 years
  • Sex: Female
  • Occupation: Retired teacher

Chief Complaint

"I have terrible abdominal pain that doesn't match what the doctors are finding on exam."

History of Present Illness

The patient presents with a 6-hour history of acute onset, severe, diffuse abdominal pain. She describes the pain as constant and "the worst she's ever felt." She had one episode of bloody diarrhea. She notes the pain seems out of proportion to what the doctors are finding when they examine her abdomen. She has a history of atrial fibrillation and admits to being non-compliant with her anticoagulation.

Past Medical History

  • Atrial fibrillation (not on anticoagulation - stopped due to "bleeding concerns")
  • Hypertension
  • Peripheral vascular disease
  • Coronary artery disease (prior MI)
  • Congestive heart failure (EF 40%)

Medications

  • Aspirin 81 mg daily (stopped warfarin 6 months ago)
  • Metoprolol 50 mg BID
  • Lisinopril 20 mg daily
  • Furosemide 40 mg daily

Physical Examination

  • Vitals: BP 98/60 mmHg, HR 112 bpm (irregularly irregular), RR 24/min, Temp 37.8°C
  • General: Elderly female in severe distress, restless
  • Cardiovascular: Irregular rhythm, no murmurs
  • Abdomen:
  • Initially: Soft, mild diffuse tenderness, NO peritoneal signs
  • "Pain out of proportion to physical exam" - classic finding
  • Bowel sounds: Initially present but hypoactive
  • No distension
  • Extremities: Evidence of peripheral vascular disease

Laboratory Results

  • WBC: 18,400/μL (left shift)
  • Hemoglobin: 14.8 g/dL (hemoconcentrated)
  • Lactate: 5.8 mmol/L (markedly elevated)
  • pH: 7.28 (metabolic acidosis)
  • Base deficit: -8
  • D-dimer: Elevated
  • Creatinine: 1.6 mg/dL

Imaging

CT Angiography (CTA) Abdomen:

  • Filling defect in the superior mesenteric artery (SMA) - embolic occlusion
  • Diminished enhancement of jejunal and ileal segments
  • Bowel wall thickening
  • Pneumatosis intestinalis in several loops (ominous sign)
  • No portal venous gas

Diagnosis

Acute mesenteric ischemia - SMA embolism

Immediate Management

  1. Aggressive fluid resuscitation
  2. Broad-spectrum antibiotics
  3. Correct acidosis
  4. Anticoagulation with heparin
  5. Emergent surgical exploration

Operative Procedure

Emergency exploratory laparotomy:

  • Findings: Ischemic jejunum and proximal ileum (200 cm involved)
  • SMA explored - embolectomy performed via arteriotomy
  • Excellent pulsatile flow restored after embolectomy
  • Bowel reassessed after warm packs and time:
  • 80 cm of frankly necrotic bowel
  • Remaining bowel with questionable viability
  • Resection of necrotic bowel
  • Bowel left in discontinuity (damage control)
  • Temporary abdominal closure
  • Planned second-look laparotomy in 24-48 hours

Second-Look Laparotomy (48 hours)

  • Remaining bowel viable with good color and peristalsis
  • Primary anastomosis performed (hand-sewn)
  • 120 cm of small bowel remaining
  • Abdomen closed

Postoperative Course

  • ICU care for 5 days
  • Prolonged ileus
  • Transitioned to TPN
  • Eventually tolerating enteral nutrition
  • Anticoagulation with warfarin initiated (goal INR 2-3)
  • Discharged to rehabilitation on POD 14

Long-Term Management

  • Lifelong anticoagulation for atrial fibrillation
  • Nutritional monitoring (short bowel concerns)
  • May need supplemental nutrition support

Teaching Points

  1. Classic triad: Severe pain, pain out of proportion to exam, risk factor for embolism
  2. Atrial fibrillation without anticoagulation is major risk factor
  3. Lactate elevation indicates bowel ischemia
  4. CTA is imaging modality of choice
  5. Prompt revascularization is critical
  6. Second-look laparotomy appropriate for questionable bowel viability
  7. Delay in diagnosis dramatically increases mortality (>70% if bowel necrosis)

Clinical Image

Image Description: CT angiography demonstrating filling defect in the superior mesenteric artery consistent with embolic occlusion. Associated findings include bowel wall thickening and decreased mucosal enhancement of the affected small bowel segments.

Attribution: Image from Wikimedia Commons. Source: https://commons.wikimedia.org/wiki/Category:Computed_tomography_angiography

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