[Significance of drains in surgery].

Placing drains is one the most common procedures following operations in surgical disciplines. The indication for placing a drain is, however, usually based on a traditional belief rather than being evidence-based. This paper presents an overview of the literature regarding the indications and the evidence level for placing drains following operations in visceral, vascular, thoracic and orthopeedic surgery as well as traumatology. In visceral surgery the indications for placing drains could be clarified over the past decades but in other surgical fields the level of evidence needs further investigation and clarification through future studies. The available data suggest that in most cases a prophylactic drainage can be avoided. In addition, drains may lead to increased morbidity and higher treatment costs.