## Radiological Diagnosis: Consolidation **Key Point:** The presence of air bronchograms within an opaque area is pathognomonic for consolidation, not collapse. Air bronchograms indicate that the bronchi remain patent and air-filled while the surrounding alveoli are filled with fluid, pus, or blood. **High-Yield:** Air bronchograms = consolidation (pneumonia, pulmonary oedema, aspiration). Absence of air bronchograms = collapse or pleural effusion. ### Consolidation vs Collapse: Key Differentiating Features | Feature | Consolidation | Collapse | |---------|---|---| | **Air bronchograms** | Present (pathognomonic) | Absent | | **Heart border visibility** | Clear (unless left lower lobe) | Silhouetted if adjacent to heart | | **Tracheal shift** | None or away from lesion | Toward the lesion | | **Diaphragm position** | Normal | Elevated on affected side | | **Volume of hemithorax** | Normal | Decreased | | **Cause** | Alveolar filling (infection, oedema, blood) | Bronchial obstruction or loss of elastic recoil | **Clinical Pearl:** In this case, the right heart border is clearly visible, ruling out left lower lobe consolidation (which would silhouette the left heart border). The presence of air bronchograms within the opacity is diagnostic of consolidation, most likely pneumonia given the acute presentation with productive cough and fever. ### Pathophysiology of Consolidation 1. Alveolar filling with inflammatory exudate, pus, or fluid 2. Loss of air in alveoli → increased density on X-ray 3. Bronchi remain patent → air within bronchi visible as linear lucencies (air bronchograms) 4. No volume loss → normal hemithorax size **Mnemonic:** **AIR BRONC** = **A**lveolar filling with **I**nflammatory exudate → **R** remains patent → **BRONC**hial air visible **Warning:** Do not confuse consolidation with collapse. Collapse shows volume loss, mediastinal shift toward the lesion, and absence of air bronchograms. 
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.