ArticlesDifferentiating Pyopneumothorax and Peripheral Lung Abscess: Chest Ultrasonography
Section snippets
Methods
Consecutive patients who had peripheral thoracic lesions containing air-fluid level shown on chest radiograms and/or chest CT scans and who were admitted to the Taipei Veterans General Hospital were eligible for this study. Patients were excluded from this study if they had one of the followings: (1) pulmonary lesion not abutting the pleura; (2) pulmonary lesion proved to be a malignant tumor with sterile necrosis; or (3) nonempyemic hydropneumothorax. Chest ultrasonography was performed within
Results
The sonographic features evaluated in differentiating lung abscess and pyopneumothorax are summarized in Table 1. The uniformity of wall width, the smoothness of luminal margin and shape of the lesion, chest wall angle, pleural separation, the presence of air-fluid level, the curtain sign, loss of gliding sign above the air-fluid level, and the suspended microbubble sign appeared to be of significant value in differentiating lung abscess from pyopneumothorax. Nevertheless, the sharpness of
Discussion
Differentiation of lung abscess and pyopneumothorax is important because the treatment of the two diseases differs significantly. Pyopneumothorax, with or without bronchopleural fistula, usually requires tube drainage, whereas lung abscess is generally treated conservatively with appropriate antibiotics and postural drainage.
By and large, chest radiography plays a limited role in differentiating pyopneumothorax and peripheral lung abscess. Several reports have documented the ability of chest CT
Conclusion
Knowledge of the panel of sonographic findings, including the presence of air-fluid level, the curtain sign, loss of gliding sign above the air-fluid level, and the suspended microbubble sign, characteristic of hydropneumothorax and pyopneumothorax should be of value to the physicians when diagnosis of a peripheral thoracic lesion with air-fluid level is problematic. With this information, chest ultrasonography can resolve the uncertainty and substantially reduce the delay in starting effective
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2016, ChestCitation Excerpt :US can reliably differentiate both as well as CT.6,7 Lung abscesses are more likely to have irregular or jagged borders and distinct separation of pleural spaces with regions of varying echogenicity when compared with pyopneumothoraces (Video 2). However, one of the best signs of differentiating between these two diagnoses is suspended microbubbles.5 In one case series of pyopneumothoraces studied with thoracic US, microbubbles were present in 18/19 cases and in no cases of lung abscesses.
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