To Study the Diagnostic Yield of Medical Rigid Thoracoscopy in Patients with Pleural Effusion of Unknown Etiology: A Cross-sectional Study

Introduction: Pleural effusion is a frequent presentation in pulmonary medicine, with 25% to 40% of exudative effusions remaining undiagnosed despite pleural fluid cytology and closed biopsy. Medical thoracoscopy (MT) enables direct pleural visualization and targeted biopsy under local anesthesia, providing a higher diagnostic yield with minimal morbidity. Aim: To evaluate the diagnostic yield and safety profile of rigid MT in patients with undiagnosed exudative pleural effusion. Materials and Methods: This descriptive cross-sectional study was conducted at the Institute of Respiratory Diseases, SMS Medical College, Jaipur, Rajasthan, India, from September 2023 to January 2025, after obtaining ethical approval. Patients aged >18 years with exudative pleural effusion requiring thoracoscopy were included. A total of 75 met the inclusion criteria. All underwent baseline hematological, biochemical, and radiological evaluation, followed by rigid thoracoscopy under local anesthesia and conscious sedation. Multiple pleural biopsies were obtained and analyzed using histopathology, immunohistochemistry, cartridge-based nucleic acid amplification test, and culture. Data were analyzed with descriptive statistics and the chi-square test, with P < 0.05 considered significant. Results: The mean ± standard deviation age was 50.8 ± 15.3 years; 57 (76%) were male and 18 (24%) were female (M:F = 3.2:1). Right-sided effusion occurred in 46 (61.3%) patients and left-sided in 28 (37.3%). The most common fluid appearance was straw-colored in 47 (62.7%), followed by hemorrhagic in 25 (33.3%) and purulent in 3 (4%). Histopathology revealed malignancy in 35 (46.7%), tuberculosis (TB) in 28 (37.3%), inflammatory conditions in 8 (10.7%), and inconclusive findings in 4 (5.3%). Adenocarcinoma was the predominant malignant subtype (20 cases; 26.7%). The overall diagnostic yield was 94.7% (71/75). The most common complication was chest pain in 47 (62.7%); no mortality was recorded. Pleurodesis was performed in 15 (20%) patients, predominantly using bleomycin (73.3%). Conclusion: Rigid MT is a safe and minimally invasive procedure with excellent diagnostic accuracy (94.7%) for undiagnosed exudative pleural effusion. It offers simultaneous therapeutic benefits with minimal complications, making it an important tool, particularly in high TB-burden areas where differentiation between infectious and neoplastic etiologies is clinically challenging.