Chest Sonography in the Diagnostic Stratification of Pleural Effusion

Abstract

Background: Pleural effusion is a common clinical finding in respiratory and systemic disorders. Differentiating between transudative and exudative effusions is critical for determining etiology and management. Conventional biochemical methods based on Light’s criteria require invasive sampling, whereas Thoracic Ultrasonography (TUS) offers a safe, bedside, radiation-free alternative capable of characterizing pleural fluid by internal echo patterns and dynamic signs.

Objectives: To evaluate the diagnostic accuracy of TUS in distinguishing exudative from transudative pleural effusions, using biochemical Light’s criteria as the reference standard.

Methods: This prospective study included 216 patients with radiologically confirmed pleural effusion attending the Department of Respiratory Medicine, Ashwini Hospital, Cuttack (May 2023-October 2024). Each underwent standardized thoracic ultrasound examination followed by diagnostic thoracentesis. Sonographic parameters-echogenicity, complexity, septations, and dynamic signs (“jellyfish,” “plankton,” “hematocrit”)-were compared with biochemical classification.

Results: Of 216 patients (mean age 54.7 ± 13.7 years; 61.1 % male), 193 (89.4 %) effusions were exudative and 23 (10.6 %) transudative by Light’s criteria. Ultrasound classified 176 (81.5 %) as exudates and 40 (18.5 %) as transudates, yielding sensitivity 91.2 %, specificity 100 %, PPV 100 %, and NPV 57.5 %. Anechoic, non-septate patterns with “jellyfish” sign correlated with transudates, whereas complex, septate, “plankton,” and “hematocrit” signs indicated exudates (p < 0.05).

Conclusion: TUS demonstrates excellent diagnostic accuracy for differentiating pleural effusions and can serve as a first-line, non-invasive diagnostic tool, particularly valuable in critical-care and resource-limited settings.