Practice Essentials
Empyema is inflammatory fluid and debris in the pleural space. It results from an untreated pleural-space infection that progresses from free-flowing pleural fluid to a complex collection in the pleural space (see the images below). Empyema most commonly occurs in the setting of bacterial pneumonia. About 20-60% of all cases of pneumonia are associated with parapneumonic effusion. With appropriate antibiotic therapy, parapneumonic effusions most often resolve without complications, and they are of little clinical significance. However, some effusions do not resolve; these are called complicated effusions. The resulting infection and inflammatory response can proceed until adhesive bands form. The infected fluid becomes loculated pus in the pleural space. Empyema affects up to 65,000 patients annually, with a mortality of approximately 15%. [1] Mortality related to empyema is associated with respiratory failure and systemic sepsis, which occurs when the immune response and antibiotics are inadequate to control the infection. [1, 2]
Empyema may also result from causes other than bacterial pneumonia. Any process that introduces pathogens into the pleural space can lead to an empyema, such as thoracic trauma (in about 1-5% of cases), rupture of a lung abscess into the pleural space, extension of a non–pleural-based infection (eg, mediastinitisabdominal infection), esophageal tear, iatrogenic introduction at the time of thoracic surgery, and an indwelling catheter that is a nidus for infection.
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Posteroanterior (PA) chest radiograph of a man in his 50s who had a 2-week history of partially treated pneumonia. He presented with persistent fever and chest pain. The patchy bilateral lung parenchymal opacities indicate pneumonia. The obliterated left costophrenic angle suggests a left pleural effusion.
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Contrast-enhanced axial computed tomography (CT) scan at the level of the inferior pulmonary veins; the patient was a man in his 50s who had a 2-week history of partially treated pneumonia. The image demonstrates loculated fluid in the left major fissure, a pseudotumor (arrow). Gas bubbles are present in the dependent collection of pleural fluid (arrowheads).
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Enhanced axial computed tomography (CT) scan a few centimeters inferior to the level in the previous image. Enhancing pleural membranes (arrows) anterior and posterior to the fluid collection indicate the split-pleura sign. The patient had pus in the pleural space; this indicated empyema. Courtesy of Judith Amorosa, MD.
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Image obtained in a patient with an empyema shows the split-pleura sign in the setting of right lower lobe (RLL) consolidation and atelectasis.
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Enhanced axial computed tomography (CT) scan obtained at the level of the aortic valve in a septic, alcoholic patient who was brought to the emergency department from a homeless shelter several days after becoming ill. Image shows several gas bubbles in a large right pleural fluid collection. An enhancing pleural membrane (arrow) defines the empyema extending into the chest wall. These are the findings of empyema necessitatis.
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Posteroanterior (PA) chest radiograph in a 52-year-old man who had severe pneumonia in his early 20s shows a large right pleural-based mass. He was treated with antibiotics for 3 days but had a high temperature and chest pain for several weeks. When this image was obtained, the patient was asymptomatic. Courtesy of Judith Amorosa, MD.
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Computed tomography (CT) scan (mediastinal window) shows a mass with a thick, calcified wall arising from the pleura with an air-fluid level. This finding represents an organized, walled-off, old empyema. Courtesy of Judith Amorosa, MD.
