[Medical principles of thromboembolism prevention].

Since thromboembolic complications have been described to be one of the most frequent complications following surgery, a correct indication for prophylaxis is of great clinical importance. This requires comprehensive knowledge about the general thrombosis risk of various patient populations, experience in the assessment of the individual thrombosis risk, understanding of the mode of action of various prophylaxis modalities, and critical benefit/risk assessment when pharmacological agents are used. Patients with a moderate or high risk require medical prophylaxis with either unfractionated heparin, low molecular weight heparins, or oral anticoagulants unless there is too high a risk of bleeding. Mechanical methods such as physical exercise and early mobilisation of the patient remain the basic measurements which can be supplemented by graduated pressure stockings.