[Diagnostic approaches in pleural effusion]

It is not easy to discover the underlying cause for pleural effusion. Over a quarter of the pleural effusions remain unexplained by indirect methods of examination such as chemical, cytological or bacterial tests. Thoracoscopy however, shows impressive results and can be conducted under simple conditions. Different statistical collections allow for the assumption that pleural effusions due to cardiac disease and malignant conditions occur equally often. They are followed in frequency by infection diseases and the often misjudged effusion with pulmonary embolism.