Cholecystopulmonary Fistula Detection on CT
Yes, a fistula from the gallbladder to the lungs would likely be visible on CT scan with contrast, though this is an extremely rare entity with limited published data. CT imaging can detect fistulous tracts, gas in abnormal locations, and associated fluid collections that would suggest such a communication.
CT Imaging Capabilities for Fistula Detection
CT with intravenous contrast is highly effective at detecting fistulous tracts in general, with demonstrated sensitivities of 76.5% for fistula detection and 94.1% for defining underlying etiology in gastrointestinal fistulas 1. The key diagnostic features that CT can identify include:
- Enhancing fistulous tracts connecting two anatomic structures 2
- Gas in abnormal locations (such as pneumobilia or gas within fluid collections) 1
- Focal wall thickening at the sites of communication 2
- Associated fluid collections or abscesses along the tract 1
Specific Evidence for Cholecystothoracic Fistula
While cholecystopulmonary fistulas are exceedingly rare, there is documented case evidence of CT successfully identifying cholecyst-thoracic fistula. In a reported case, CT scan revealed cholecystitis with subsequent surgical confirmation of fistulization toward the thorax with passage of biliary calculi into the chest cavity 3. This demonstrates that CT can detect this rare complication when it occurs.
Optimal CT Protocol
For suspected biliary-thoracic fistula, CT should be performed without and with IV contrast to maximize detection 1. The protocol should include:
- Non-contrast phase to identify inherently hyperdense material, calculi, and baseline gas patterns 1
- Arterial and portal venous phases to enhance visualization of inflammatory changes and vascular structures 1
- Extended field of view covering both abdomen and lower chest to capture the entire potential fistulous tract 3
Oral contrast should be avoided as it can obscure subtle findings and interfere with detection of contrast extravasation 1.
Clinical Context and Pitfalls
Cholecystopulmonary fistulas typically occur as a complication of long-standing cholecystitis with chronic inflammation, similar to other cholecystoenteric fistulas 4, 5, 6. Key clinical clues include:
- Recurrent right basal pneumonia that may represent the presenting symptom 3
- History of chronic cholecystitis or cholelithiasis 3, 6
- Signs of complicated biliary disease on imaging 3
The main diagnostic pitfall is not considering this rare diagnosis in patients with recurrent pneumonia and known biliary disease. CT may show findings of cholecystitis without the radiologist specifically identifying the fistulous communication unless there is high clinical suspicion 3.
Complementary Imaging
If CT findings are equivocal, MRI with contrast provides superior soft tissue resolution and may better delineate complex fistulous anatomy 7. However, CT remains the first-line modality due to wider availability and faster acquisition 2.