What is the role of an esophagram (esophageal swallow study) in diagnosing and managing a patient with pneumomediastinum and suspected esophageal injury?

Esophagram for Pneumomediastinum

Contrast-enhanced CT with CT esophagography is the imaging examination of choice for pneumomediastinum, and routine esophagography is not necessary when CT shows no signs of esophageal perforation. 1, 2

Primary Diagnostic Approach

CT imaging alone is sufficient for most patients with pneumomediastinum. The sensitivity and negative predictive value of CT for detecting esophageal perforation are 100%, which equals or exceeds fluoroscopic esophagography. 2 CT detects pneumomediastinum in 100% of cases, compared to only 15% detection rate on plain radiographs. 3

CT Findings That Indicate Esophageal Injury

Proceed directly to esophagography or endoscopy only if CT demonstrates:

• Periesophageal fluid collections (present in 89-92% of perforations) 4
• Extraluminal air adjacent to the esophagus (present in 97% of perforations) 4
• Esophageal wall thickening with periesophageal infiltration (present in 72-75% of perforations) 4, 2
• Focal wall defects or absence of post-contrast wall enhancement (indicates transmural necrosis) 4
• Mediastinal fat stranding 4

When to Skip Esophagography

Do not perform esophagography in patients with pneumomediastinum when:

• CT shows no evidence of esophageal injury or periesophageal infiltration 2
• No history of esophageal instrumentation, forceful vomiting, or trauma 5, 6
• No pleural effusion on imaging 5
• Patient is clinically stable without signs of mediastinitis 6

Multiple studies confirm that esophagography adds no diagnostic value when CT is negative. In one series of 103 patients with pneumomediastinum but negative CT findings for esophageal injury, zero cases of esophageal perforation were missed. 2 Another study of 25 patients with spontaneous pneumomediastinum found all esophagographies and esophagoscopies were negative, and no patients developed complications. 6

High-Risk Scenarios Requiring Esophageal Evaluation

Proceed with esophagography or endoscopy when clinical predictors suggest esophageal injury:

• Recent esophageal instrumentation (odds ratio 45.7 for esophageal injury) 5
• Pleural effusion on imaging (odds ratio 10.5 for esophageal injury) 5
• History of forceful vomiting or retching (odds ratio 9.3 for esophageal injury) 5
• CT findings suspicious for perforation as listed above 1, 4

In trauma patients with pneumomediastinum, only 1% have esophageal injuries and 4% have airway injuries. 3, 5 The incidence is even lower in spontaneous pneumomediastinum. 7, 6

Optimal Esophageal Imaging Protocol When Indicated

If esophagography is necessary based on the above criteria:

• Use water-soluble contrast (Gastrografin) rather than barium to avoid impairing subsequent endoscopy and because barium is contraindicated in perforation 4
• Perform imaging 3-6 hours after suspected injury when possible to assess full extent 4
• Include coverage of neck, chest, and abdomen 4

Consider flexible endoscopy instead of or in addition to esophagography when CT findings are equivocal, as endoscopy combined with CT allows accurate diagnosis in >90% of cases and alters management in 69% of patients. 4 Use low-flow CO2 insufflation rather than air to minimize risk of enlarging any perforation. 4

Critical Pitfalls to Avoid

• Do not order routine esophagography for all pneumomediastinum cases—this represents unnecessary testing when CT is negative for esophageal injury 2, 6
• Do not rely on plain chest radiographs alone, which have up to 47% false-negative rate and miss 85% of pneumomediastinum cases 4, 3
• Do not use barium contrast if esophagography is performed, as it impairs subsequent procedures 4
• Do not delay treatment beyond 24 hours if esophageal perforation is confirmed, as mortality increases from <10% to 30% with delayed management 4