COMPARATIVE STUDY OF ULTRASOUND AND X-RAY IN PLURAL EFFUSION

Abstract

Background: Pleural effusion is a common clinical manifestation of diverse cardiopulmonary and systemic diseases. Chest X-ray (CXR) has traditionally been the first-line imaging modality for its detection, but it possesses well-documented limitations in sensitivity and characterization. Thoracic ultrasound (USG) has emerged as a superior, bedside alternative, offering real-time visualization and enhanced diagnostic accuracy.

Objective: This study aimed to compare the diagnostic performance of chest X-ray and thoracic ultrasound in detecting and characterizing pleural effusion, and to evaluate their impact on clinical assessment.

Methodology: A prospective, observational, comparative study was conducted over four months. A total of 165 adult patients (aged ≥18 years) with clinical suspicion of pleural effusion were enrolled. All participants underwent both standard chest X-ray (digital radiography) and thoracic ultrasound examination using a portable device with a 3.5–5 MHz curvilinear probe. Exclusion criteria included age <18 years, prior pleural surgery, hemodynamic instability, refusal to consent, poor imaging windows, and pregnancy. Data on clinical presentation, imaging findings, and effusion characteristics were systematically collected and analyzed.

Results: The cohort comprised 89 males (53.9%) and 76 females (46.1%). Dyspnea was the most common symptom (54.5%). Chest X-ray detected effusion in 83 patients (50.3%), with a near-equal distribution between right-sided (32.1%), left-sided (33.9%), and bilateral (33.9%) presentations. Ultrasound confirmed effusion in 83 patients (50.3%) but provided superior characterization, identifying septated (34.5%), anechoic (33.3%), and complex (32.1%) morphologies. Cross-tabulation revealed 15 false-negative CXRs (ultrasound-positive/CXR-negative) and 18 false-positive CXRs (CXR-positive/ultrasound-negative). Ultrasound also identified ancillary findings such as pleural thickening (49.1%) and abnormal diaphragmatic movement (44.2%) not appreciable on CXR.

Conclusion: Thoracic ultrasound demonstrates superior diagnostic accuracy compared to chest X-ray in the evaluation of pleural effusion, with fewer false negatives and enhanced characterization of effusion complexity. Its ability to detect additional pleural and diaphragmatic pathology makes it an indispensable tool in clinical decision-making. These findings support the integration of ultrasound as a primary imaging modality in the diagnostic pathway for suspected pleural effusion to improve detection, guide management, and optimize patient outcomes.