Diagnosis of Lung Abscess Chest x-ray Often chest CT for better visualization or if endobronchial obstruction is suspected Sputum cultures for aerobic bacteria, fungi, and mycobacteria Bronchoscopy as needed to exclude cancer, detect unusual pathogens such as fungi or mycobacteria, and in immunocompromised patients Culture of any pleural fluid Lung abscess is suspected based on history in a patient who is at risk (eg, aspiration-prone due to altered consciousness or dysphagia or who is immunosuppressed) and is confirmed by chest x-ray showing cavitation.