What is the best imaging modality for diagnosing tracheo-esophageal (TE) fistula?

Best Imaging Modality for Diagnosing Tracheo-Oesophageal Fistula

Combined bronchoscopy and endoscopy is the gold standard for diagnosing tracheo-oesophageal fistula (TEF), providing direct visualization of the fistula with the highest diagnostic accuracy. 1

Primary Diagnostic Approaches

Endoscopic Evaluation

• Flexible bronchoscopy combined with simultaneous oesophageal endoscopy is considered the gold standard for diagnosing TEF, particularly recurrent TEF 1
• This combined approach allows direct visualization of the fistula site and has the highest diagnostic accuracy 1
• During bronchoscopy, positive pressure insufflation, dye or contrast injection, and gentle probing can assist with fistula identification 1
• The TEF Respiratory Complications Recommendations (TEF-RCR) specifically considers combined bronchoscopy and endoscopy to be the gold standard for diagnosis of recurrent TEF 1

Contrast Studies

• Upper gastrointestinal 'pull-back' study is particularly effective for diagnosing small TEFs 1
  • This technique involves injecting contrast under pressure using catheters in the oesophagus, forcing contrast through small fistulae 1
• Traditional contrast (gastrografin/barium) esophagogram can miss up to 30% of small esophageal perforations 1
• A contrast swallow study may identify TEF but has lower sensitivity than the pull-back technique 2

CT Imaging

• CT esophagogram has high sensitivity (95%) and specificity (91%) for detecting upper digestive tract perforations 1
• Contrast-enhanced CT can show indirect signs of TEF such as paraesophageal collections, free air, and pleural effusions 1
• CT has largely replaced traditional contrast esophagogram in many centers due to its higher sensitivity and ability to provide additional information about surrounding structures 1
• Three-dimensional CT reconstruction and virtual bronchoscopy can be useful in pre-operative evaluation of TEF 3

Diagnostic Algorithm

1. Initial Assessment:

   • For patients with suspected TEF, begin with a contrast-enhanced CT with CT esophagography if the patient is hemodynamically stable 1
   • This provides information about the fistula and any associated conditions

2. Definitive Diagnosis:

   • Proceed to combined flexible bronchoscopy and esophageal endoscopy for direct visualization and confirmation 1
   • This combination allows for the most accurate diagnosis, with identification rates exceeding 90% 1

3. For Difficult Cases:

   • If initial studies are equivocal but clinical suspicion remains high, perform an upper gastrointestinal 'pull-back' study with contrast injection under pressure 1
   • This technique is particularly valuable for identifying small recurrent TEFs that might be missed by standard imaging 1

Special Considerations

• In intubated or unstable patients, intraoperative endoscopy can be employed to rule out esophageal perforation 1
• For patients at high risk of aspiration, a pull-back tube esophagogram may be safer than a standard contrast swallow 2
• In cases of recurrent TEF following previous repair, a high index of suspicion should be maintained as there is often a delay in diagnosis 1
• For congenital H-type TEF without esophageal atresia, contrast swallow studies may be sufficient in most cases, with pull-back studies reserved for equivocal cases 2

Pitfalls and Caveats

• Nasogastric tube-administered contrast may miss esophageal perforation during contrast studies 1
• During endoscopy, excessive insufflation may promote mediastinal contamination by increasing the size of the perforation; low-flow insufflation and use of CO2 rather than air are recommended 1
• A negative initial imaging study does not exclude TEF if clinical suspicion is high; persistent respiratory symptoms warrant further investigation regardless of age and duration since initial repair 1
• The site of the original defect in the posterior tracheal wall is usually recognizable during bronchoscopy; however, smaller openings might be obscured by airway secretions 1