[Drainage in soft tissue surgery. What is "evidence based"?].

Due to the advanced technical possibilities, there are now up to 30 different drainage systems available for soft tissue surgery. The differences between these systems involve the mode of drainage (open into the bandage, closed into bag/bottle), the kind of suction (gravity drainage, low-vacuum and high-vacuum up to 900 mbar) and the material of the tube (PVC, silicone or polyurethane). There also exists a marked controversy about the fundamental necessity for drainage after surgery. A survey of the literature indicates that there is a distinct discrepancy between scientific knowledge and daily routine action. For primarily uninfected wounds, the application of an open drainage system,with the secretion going directly into the bandage, is obsolete. Gravity drainage systems guarantee just as effective secretion drainage in comparison to high vacuum drainage according to Redon. In soft tissue wounds, high-vacuum suction leads to the sucking in of tissue and blood,whereby comparatively elevated quantities of secretion can be produced. During the removal of Redon-drainage, there is stronger pain than on the removal of gravity drainage systems consisting of silicone or polyurethane. Prophylactic insertion of drainage in uncomplicated thyroid surgery and for hernia repair is not necessary. Insertion of drainage for up to 72 h is not accompanied by an elevated infection rate. The routine microbiological examination of the tip of the drainage tube is not recommended.