Determining the Diagnostic Yield and Pathological Spectrum of Thoracoscopy in Patients with Undiagnosed Exudative Pleural Effusion

Abstract

Background: Roughly one in five exudative pleural effusions remains undiagnosed after initial evaluation. Medical thoracoscopy allows targeted pleural biopsy, but its yield and pathological spectrum vary with regional tuberculosis burden and patient characteristics.

Objective: To determine the diagnostic yield and delineate the pathological spectrum of thoracoscopy in patients with undiagnosed exudative pleural effusion.

Materials and Methods: This descriptive cross-sectional study was conducted at the Department of Pulmonology, Lahore General Hospital, Lahore, from September 2025 to March 2026. Sixty-two patients aged 18–60 years with exudative pleural effusion, negative GeneXpert testing, and twice-negative pleural fluid cytology were enrolled through non-probability consecutive sampling. Medical thoracoscopy with targeted pleural biopsy was performed, and specimens underwent histopathological examination. Diagnostic yield was calculated with exact 95% confidence intervals (CIs). Stratified comparisons were performed using the chi-square or Fisher exact test, with p < 0.05 considered statistically significant.

Results: The mean age was 39.6 ± 10.7 years, and 36 patients (58.1%) were male. A histopathological diagnosis was established in 55 patients (diagnostic yield 88.7%; 95% CI 78.1–95.3). Tuberculous pleurisy was the most frequent diagnosis (29 patients; 46.8%), followed by malignant pleural effusion (17; 27.4%) and inflammatory pleuritis (9; 14.5%); 7 patients (11.3%) remained undiagnosed. Diagnostic yield did not differ by age group (93.8% vs 83.3%; p = 0.249), sex (88.9% vs 88.5%; p = 1.000), or duration of symptoms (87.5% vs 89.1%; p = 1.000).

Conclusion: Thoracoscopy established a histopathological diagnosis in nearly nine of ten patients, with tuberculosis the leading cause.