What is the appropriate workup for a patient with 1 week of nausea, vomiting, and diarrhea after traveling to Mexico, without fever or chills, and a CT (computed tomography) chest showing pneumomediastinum?

Workup for Traveler's Diarrhea with Pneumomediastinum

The patient with traveler's diarrhea and pneumomediastinum requires both stool testing for persistent infectious diarrhea and evaluation of the pneumomediastinum, which is likely secondary to severe vomiting but requires exclusion of esophageal perforation.

Traveler's Diarrhea Workup

Initial Assessment

• Duration: 1 week of symptoms after Mexico travel indicates persistent traveler's diarrhea
• Severity: Nausea, vomiting, and diarrhea without fever suggests moderate severity
• Complications: Pneumomediastinum likely secondary to severe vomiting episodes

Recommended Testing

1. Microbiologic testing of stool

   • Indicated for persistent symptoms (>1 week) and those who fail empiric therapy 1, 2
   • Should include:
     • Stool culture for bacterial pathogens
     • Ova and parasite examination
     • Giardia and Cryptosporidium antigen testing
     • Clostridium difficile testing (especially if antibiotics were taken)

2. Molecular multipathogen testing

   • Preferred when rapid results are needed 1, 2
   • PCR panels can detect multiple bacterial, viral, and parasitic pathogens

Pneumomediastinum Evaluation

Imaging Studies

1. CT chest with oral and IV contrast

   • Already performed showing pneumomediastinum
   • Additional contrast study needed to evaluate for:
     • Esophageal perforation (Boerhaave's syndrome) 3
     • Extent of mediastinal air
     • Subcutaneous emphysema

2. Esophagogram with water-soluble contrast

   • Critical to rule out esophageal perforation in context of vomiting 3
   • Should be performed before endoscopy if perforation is suspected

3. Consider upper endoscopy

   • If esophagogram is negative but clinical suspicion for perforation remains high
   • Can identify mucosal tears or other esophageal pathology

Management Approach

Traveler's Diarrhea Treatment

• For moderate symptoms without fever:
  • Azithromycin is preferred (500mg daily for 3 days or single 1000mg dose) 2
  • Loperamide as adjunctive therapy (4mg initially, then 2mg after each loose stool, max 16mg/day) 1, 2

Pneumomediastinum Management

• Most cases of spontaneous pneumomediastinum are self-limiting 4, 5
• Conservative management with:
  • Oxygen supplementation if needed
  • Pain control
  • Avoidance of maneuvers that increase intrathoracic pressure
  • Close observation for 24-48 hours

Red Flags Requiring Urgent Intervention

• Worsening respiratory distress
• Signs of sepsis or peritonitis
• Evidence of esophageal perforation on imaging
• Hemodynamic instability

Follow-up

• Resolution of pneumomediastinum should be confirmed with repeat imaging
• If diarrhea persists beyond 14 days despite treatment, consider:
  • Post-infectious irritable bowel syndrome 1, 2
  • Resistant organisms
  • Parasitic infections requiring specific therapy

Important Considerations

• Spontaneous pneumomediastinum from vomiting can mimic Boerhaave's syndrome (esophageal rupture), but the latter is a surgical emergency requiring immediate intervention 3
• Air can dissect from the mediastinum into the peritoneum, causing pneumoperitoneum without intestinal perforation 6
• The pneumomediastinum will typically resolve spontaneously within days to weeks with conservative management 4, 5, 7