Diagnostic imaging for CAP in adults
Evidence of new pulmonary consolidation seen on chest X-ray (with both posterior-anterior [PA] and lateral views if possible) usually establishes the diagnoses of CAP. If clinical features suggest CAP, perform a chest X-ray for adultsRamirez, 2020:
- with moderate- or high-severity CAP
- who have an unclear diagnosis (eg unexplained hypoxia, significant breathlessness)
- with comorbid lung disease, immune compromise or advanced age
- who are not improving if imaging was not initially performed
- to look for complications of pneumonia (eg parapneumonic effusion and empyema, lung abscess).
Other diagnostic imaging modalities for pneumonia include:
- computed tomography (CT) of the chest (including low-dose CT) – if indicated to exclude other differential diagnoses (eg pulmonary embolism)Claessens, 2022Claessens, 2015van den Berk, 2022
- ultrasound – to demonstrate consolidation; however, this requires a trained and experienced operator, and it lacks specificity. It may have a role if other imaging modalities are not availableRodriguez-Contreras, 2022.
Infiltrates seen on diagnostic imaging can take weeks to resolve. Most adults with CAP do not require follow-up diagnostic imaging; however, it may be required 6 to 8 weeks after the episode of pneumonia in some patients (eg patients with risk factors for lung cancer, those who have not improved).
For a list of other clinical and microbiological investigations for CAP in adults, see Clinical and microbiological investigations for community-acquired pneumonia (CAP) in adults.