[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Conditions](https://durgical.com/en/conditions/) › Lung abscess [Conditions](https://durgical.com/en/conditions/) · [Pulmonology](https://durgical.com/en/conditions/) # Lung abscess A lung abscess is a pus-filled cavity in the lung, usually after inhaling mouth bacteria. It causes fever and foul-smelling sputum. Updated 2026-11-01 ## Structures involved Tap one to see what it is and open it in 3D. - [Right lower lobe](https://durgical.com/en/anatomy/inferior-lobe-of-right-lung/) - [Main bronchi](https://durgical.com/en/anatomy/right-main-bronchus/) - [Right upper lobe](https://durgical.com/en/anatomy/superior-lobe-of-right-lung/) - [Left lower lobe](https://durgical.com/en/anatomy/inferior-lobe-of-left-lung/) - [Segmental bronchi](https://durgical.com/en/anatomy/segmental-bronchus/) - [Pleura](https://durgical.com/en/anatomy/pleura/) - [Trachea](https://durgical.com/en/anatomy/trachea/) ## In the clinical exam - [Digital clubbing and nail signs](https://durgical.com/en/clinical-exam/digital-clubbing-and-nail-signs/) - [Cavitation syndrome](https://durgical.com/en/clinical-exam/cavitation-syndrome/) ## Why it happens - [Patterns of necrosis: coagulative, liquefactive, caseous, fat, fibrinoid, gangrenous](https://durgical.com/en/general-pathology/patterns-of-necrosis-coagulative-liquefactive-caseous-fat-fibrinoid-gangrenous/) - [Outcomes of acute inflammation: resolution, abscess, scar or chronic inflammation](https://durgical.com/en/general-pathology/outcomes-of-acute-inflammation-resolution-abscess-scar-or-chronic-inflammation/) - [Patterns of acute inflammation: serous, fibrinous, purulent, abscess, ulcer](https://durgical.com/en/general-pathology/patterns-of-acute-inflammation-serous-fibrinous-purulent-abscess-ulcer/) - [Airway defenses, cough and mucociliary clearance](https://durgical.com/en/physiology/airway-defenses-cough-and-mucociliary-clearance/) ## What it is A localised area of necrosis of lung tissue caused by infection, forming a cavity larger than 2 cm that contains pus and often an air-fluid level. Smaller multiple cavities are called necrotising pneumonia. ## Who gets it Less frequent since antibiotics became widely available, but still seen in people with alcohol use disorder, seizures, poor dentition or swallowing disorders. In Colombia and Latin America, cavitary tuberculosis is a more common cause of a lung cavity and must always be excluded. ## Causes - Aspiration of oral anaerobic flora (Peptostreptococcus, Prevotella, Fusobacterium, Bacteroides) is the most common cause - Staphylococcus aureus and Klebsiella pneumoniae (necrotising pneumonia) - Septic emboli from right-sided endocarditis or septic thrombophlebitis - Bronchial obstruction by a tumour or foreign body - Mycobacteria, fungi and parasites in immunocompromised hosts ## Risk factors - Reduced consciousness: alcohol intoxication, seizures, anaesthesia, drug overdose - Dysphagia from stroke, neuromuscular disease or oesophageal disease - Poor dental hygiene and gingivitis - Injection drug use - Immunosuppression, diabetes and lung cancer ## Pathophysiology Aspirated oral bacteria cause pneumonitis that progresses to tissue necrosis in 1–2 weeks. The necrotic area liquefies and, when it drains into a bronchus, air enters and an air-fluid level forms. Gravity determines the site: lying down, aspiration goes to the posterior segments of the upper lobes and the superior segments of the lower lobes, most often on the right because the [right main bronchus](https://durgical.com/en/anatomy/right-main-bronchus/) is wider and more vertical. ## Classification - Primary: aspiration or pneumonia in an otherwise normal lung - Secondary: bronchial obstruction, septic emboli or immunosuppression - Acute (under 4–6 weeks) or chronic ## Symptoms and signs - Insidious fever, night sweats and malaise over weeks - Cough with abundant, foul-smelling and foul-tasting sputum - Pleuritic chest pain - Weight loss and anaemia in chronic cases - Haemoptysis - Poor dentition or gingivitis on examination; digital clubbing in chronic cases ## Red flags - Massive haemoptysis - Sepsis or respiratory failure - Sudden worsening with pleural fluid (rupture into the [pleura](https://durgical.com/en/anatomy/pleura/), empyema) - Abscess that does not shrink after weeks of antibiotics (suspect tumour or resistant organism) - Older smoker without aspiration risk (suspect cancer) ## Diagnosis **Clinical** Suspected in a person with aspiration risk, subacute fever and foul sputum. Assessment of dentition, swallowing and level of consciousness. **Tests** Blood count, blood cultures, sputum Gram stain and culture (anaerobes are hard to grow from sputum); acid-fast smears, molecular test and culture for tuberculosis in every cavity; fungal studies when immunosuppressed. Bronchoscopy when obstruction or cancer is suspected or the response is poor. **Imaging** [Chest](https://durgical.com/en/anatomy/region/chest/) X-ray: thick-walled cavity with an air-fluid level in a dependent segment. CT defines the cavity, distinguishes abscess from empyema (abscess forms acute angles with the chest wall) and looks for an obstructing lesion. ## Differential diagnosis - Cavitary pulmonary tuberculosis - Cavitating lung cancer (squamous cell carcinoma) - Empyema with bronchopleural fistula - Granulomatosis with polyangiitis - Infected bulla or cyst, aspergilloma ## Goal of treatment Eradicate the infection, allow the cavity to drain and close, and correct the cause of aspiration or obstruction. ## Treatment **Medical** Prolonged antibiotics with anaerobic activity (e.g. a beta-lactam with beta-lactamase inhibitor, or clindamycin), often for several weeks until the X-ray improves. **Conservative** Postural drainage and chest physiotherapy, nutrition support and dental care. **Procedure** Percutaneous or endoscopic drainage for large abscesses that do not respond; bronchoscopy to remove a foreign body or assess a tumour. **Surgical** Lobectomy for failure of medical treatment, massive haemoptysis or suspected cancer. ## Complications - Empyema and bronchopleural fistula - Massive haemoptysis - Spread of infection to other lung areas - Bronchiectasis and residual cavity - Brain abscess and sepsis ## Prognosis Most primary abscesses heal with prolonged antibiotics. Outcomes are worse in older patients, immunosuppressed hosts, large cavities, Klebsiella or Staphylococcus infections and abscesses secondary to bronchial obstruction or cancer. ## Prevention - Aspiration precautions in patients with dysphagia or reduced consciousness (head of bed elevated, swallowing assessment) - Dental hygiene and treatment of periodontal disease - Treatment of alcohol use disorder ## Test yourself Think of the answer, then tap the question to see it. ## What is the most common cause of a primary lung abscess? Aspiration of oral anaerobic bacteria in people with reduced consciousness, dysphagia or poor dentition. ## Which lung segments are most often affected after aspiration in a supine patient? The posterior segments of the upper lobes and the superior segments of the lower lobes, more often on the right. ## What is the classic radiological sign of a lung abscess? A thick-walled cavity with an air-fluid level. ## Which disease must always be excluded in Colombia when a lung cavity is found? Pulmonary tuberculosis, with acid-fast smears, molecular testing and mycobacterial culture. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/conditions/lung-abscess/) ## Related conditions - [Aspiration pneumonia and pneumonitis](https://durgical.com/en/conditions/aspiration-pneumonia-and-pneumonitis/) - [Parapneumonic effusion and empyema](https://durgical.com/en/conditions/parapneumonic-effusion-and-empyema/) - [Alcohol use disorder](https://durgical.com/en/conditions/alcohol-use-disorder/) - [Community-acquired pneumonia](https://durgical.com/en/conditions/community-acquired-pneumonia/) - [Pulmonary tuberculosis](https://durgical.com/en/conditions/pulmonary-tuberculosis/) - [Lung cancer](https://durgical.com/en/conditions/lung-cancer/) - [Granulomatosis with polyangiitis](https://durgical.com/en/conditions/granulomatosis-with-polyangiitis/) - [Bronchiectasis](https://durgical.com/en/conditions/bronchiectasis/) - [Oropharyngeal dysphagia in older adults](https://durgical.com/en/conditions/oropharyngeal-dysphagia-in-older-adults/) - [Periodontitis](https://durgical.com/en/conditions/periodontitis/) - [Aspergillosis](https://durgical.com/en/conditions/aspergillosis/) Educational information, not medical advice. For any symptom, see a health professional. Sources: [Abscess in the Lungs](https://www.merckmanuals.com/home/lung-and-airway-disorders/abscess-in-the-lungs/abscess-in-the-lungs) (Merck Manual Consumer Version, 2024). [← All conditions](https://durgical.com/en/conditions/) ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/conditions/lung-abscess/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/lung-abscess/