Thoracoscopy involves a percutaneous approach to placement of an endoscopic instrument within the pleural space, allowing direct visualization and biopsy of the pleura. Unlike video-assisted thoracic surgery (VATS), in which the surgeon uses a thoracoscope to assist with performance of minimally invasive surgery, the purpose of "medical thoracoscopy" is to provide access to the pleura for evaluation and, in some cases, management of pleural disease . Open pleural biopsy is now largely done during medical thoracoscopy.
The major indication for diagnostic medical thoracoscopy is an exudative pleural effusion of unknown etiology. Often at the time of thoracoscopy, the etiology turns out to be mesothelioma, lung cancer, tuberculosis, or a benign pleural disorder. In some hands, medical thoracoscopy is used to evaluate pulmonary parenchymal disease.
An overview of thoracoscopy and the therapeutic indications for thoracoscopy are discussed separately. (See "An overview of medical thoracoscopy" and "Therapeutic uses of medical thoracoscopy".)
PLEURAL EFFUSION OF UNKNOWN ETIOLOGY
Algorithms for investigating pleural effusions of unknown etiology typically begin with thoracentesis. (See "Diagnostic evaluation of pleural effusion in adults: Additional tests for undetermined etiology".) Pleural fluid is analyzed for cellular contents, chemistries, smears and culture of microorganisms, and cytology. However, cytological examination of even large effusions is diagnostic in only 60 to 80 percent of patients with metastatic pleural involvement [2-4] and fewer than 20 percent of patients with mesotheliomas . Thoracentesis with percutaneous closed needle biopsy may be diagnostic in 60 percent of malignant pleural effusions [6,7].
Thoracoscopy in patients with a pleural effusion of unclear etiology often yields a specific diagnosis. As an example, in a series of 1000 consecutive patients with pleural effusions, 215 patients had pleural effusions of unknown etiology despite repeated thoracentesis and percutaneous needle biopsy of the pleura . Thoracoscopy resulted in a diagnosis of malignancy in 150 (70 percent) of the patients, including mesothelioma in 35 patients. Similar levels of diagnostic accuracy have been reported by other investigators [8-13].