Thoracoscopy for the diagnosis of pleural disease. OBJECTIVE: To assess the accuracy and safety of thoracoscopy for the evaluation of pleural disease. DESIGN: Prospective evaluation of patients referred for thoracoscopy. SETTING: University hospital specializing in chest diseases. PATIENTS: We studied 102 patients with pleural disease, the cause of which had not been determined after initial investigation, including thoracentesis and needle biopsy. Eighty-six patients had pleural effusion, 11 had pleural mass, and 5 had pleural effusion in association with a known primary lung carcinoma. INTERVENTION: All patients had thoracoscopy under local anesthesia with mild sedation. Visually directed biopsies were done of parietal pleura. MEASUREMENTS: We recorded clinical characteristics, laboratory data, findings and duration of thoracoscopy, and any complications associated with the procedure. Hospital and clinic follow-up records were reviewed, and patients were contacted by telephone 12 and 24 months after thoracoscopy to assess their health status. MAIN RESULTS: One hundred and four thoracoscopies were done in 102 patients. A definitive diagnosis was established in 95 patients: 42 had malignant pleural disease and 53 had benign pleural disease. A diagnosis of benign pleural disease using thoracoscopy could not be confirmed in the remaining 7 patients because of insufficient follow-up information. Overall, thoracoscopy was 96% accurate with a sensitivity of 91%, a specificity of 100% and a negative predictive value of 93% for the diagnosis of pleural malignancy. Thoracoscopy was well tolerated under local anesthesia and entailed hospitalization for less than 24 hours in most cases. No deaths occurred, although 1.9% of patients had major complications, and 5.5% had minor complications. CONCLUSIONS: Among patients with pleural disease remaining undiagnosed after usual initial investigation, thoracoscopy done under local anesthesia is a rapid, safe, and well-tolerated procedure with an excellent diagnostic yield that is equivalent to that of thoracotomy. 