<prompt> Which of the following is the best way of preventing the development of deep vein thrombosis DVT in the postoperative period?Early ambulationPhysiotherapyProphylactic heparinLow dose aspirin  <response>: Patients are at increased risk for developing venous thromboembolism after:Major abdominal surgeryMajor orthopaedic surgeryHas sustained major traumaHas prolonged immobility 3 daysThese patients need some form of prophylaxis. The prophylaxis can be mechanical or pharmacological.Prophylaxis for DVT Mechanical Prophylaxis include : Early ambulation It is the simplest method of prophylaxisIt acts by activating the calf pump mechanismPneumatic compression devicesIt is the most common method of prophylaxisPneumatic compresses prevents the stasis by periodically compressing the calves.Pharmacological Prophylaxis includeUse of unfractionated heparin - Now being replaced by fractionated low molecular weight heparinUse of fractionated low molecular - Better efficacy than unfractionated heparinweight heparin - No laboratory monitoring is necessaryComparison of low molecular weight heparin LMWH with mechanical prophylaxis demonstrates superiority of low molecular weight heparin LMWH in reduction of the development of venous thromboembolic disease. Prospective trials evaluating LMWH in head injured and trauma patients have also proven the safety of LMWH with no increase in intracranial bleeding or major bleeding at other sites. In addition, LMWH shows significant reduction in the development of venous thromboembolism compared to other methods.In short, LMWH should be considered the optimal method of prophylaxis in moderate and high risk patients. Even the traditional reluctance to use heparin in high risk groups such as the multiply injured trauma patient and the injured patient must be reexamined, given the efficacy and safety profile of LMWH in multiple prospective trials. 