The fluid bronchogram sign can be seen on chest CT or ultrasound as the presence of fluid attenuation material within respiratory bronchioles with surrounding collapsed or consolidated lung.
- foreign body aspiration (children)
- endobronchial tumors
- infection (including aspergillus)
- mucus plugging
Importantly, this sign is not visible on plain radiographs since collapsed lung and bronchial fluid is indistinguishable in density.
Anechoic tubular structures representing fluid-clogged bronchi are seen within relatively echogenic collapsed lung. The absence of Doppler flow confirms that these are not vessels, but airways.
Contrast enhanced CT is required to differentiated tubular low attenuation representing fluid bronchograms from vessels. CT has the added benefit of localizing the possible cause or level of endobronchial obstruction.
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- 2. Dorne H L. "Differentiation of pulmonary parenchymal consolidation from pleural disease using the sonographic fluid bronchogram.". Radiology 158, no. 1 (1986): 41-42. .
- 3. Shin Myung S. and Kang-Jey Ho. "Fluid Bronchogram". Chest 104, no. 3 (1993): 960-962. . doi:10.1378/chest.104.3.960.