Background: 25 to 30% of pleural effusions may remain undiagnosed despite combination of pleural fluid analysis and closed pleural biopsy. Medical Thoracoscopy may help the physicians to diagnose such cases.

Aims and Objectives : Study the diagnostic yield of medical thoracoscopy in patients with undiagnosed exudative pleural effusion and assess the safety of the medical thoracoscopy.

Methods : Cross sectional study was done in 75 patients of undiagnosed pleural effusion. Medical thoracoscopy (MT) was done using Olympus Semi Rigid Thoracoscope (LTF 160 Evis Pleuravideoscope, Japan) under local anesthesia. Multiple pleural biopsies were taken and sent for Histopathology examination, nucleic acid amplification test and MTB culture. After the procedure, intercostal tube was inserted and patients were observed for post procedural complications.

Result: Seventy five patients were enrolled for the study. The mean ± S.D. age was 55.6 ±13.2 years. 57% (43) patients were males. MT established definitive diagnosis in 89.3% (67) patients. Thoracic malignancy was most common diagnosis, seen in 48% (36), followed by tuberculosis in 28% (21) patients. Adenocarcinoma seen in 69.4% (25) was most frequent histological type. 5.3% (4) patients had dual aetiology both tuberculosis and malignancy. Mild chest pain following the procedure was seen in 93.3%. One patient developed pneumomediastinum and was managed conservatively. There were no major adverse events after the procedure.

Conclusion: MT is safe and useful diagnostic tool in undiagnosed pleural effusions. Dual aetiologies do occur in real life clinical presentations, needs to be confirmed histopathology. Overtly relying of pleural fluid markers can delay the diagnosis.