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.
The presence of this sign suggests endobronchial obstruction as a precipitating cause for consolidation/collapse 1. This can result from a number of processes:
- foreign body aspiration (children)
- endobronchial tumours
- infection (including aspergillus)
- mucus plugging
Importantly, this sign is not visible on plain radiographs since collapse lung and boronchial 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, and infact airways.
Contrast enhanced CT is required to differentiated tubular low attenuation representing fluid bronchograms from vessels. CT has the added benefit of localising the possible cause or level of endobronchial obstruction.
- 1. Shin Myung S. and Kang-Jey Ho. "CT fluid bronchogram: Observation in postobstructive pulmonary consolidation". Clinical Imaging 16, no. 2 (1992): 109-113. . doi:10.1016/0899-7071(92)90122-p.
- 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.