This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'Which of the following is the best way of preventing the development of deep vein thrombosis (DVT) in the postoperative period? \nSelect and explain. \nA. Early ambulation, B. Physiotherapy, C. Prophylactic heparin, D. Low dose aspirin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Patients are at increased risk for developing venous thromboembolism after:\n\nMajor abdominal surgery\nMajor orthopaedic surgery\nHas sustained major trauma\nHas prolonged immobility (>3 days)\n\nThese patients need some form of prophylaxis. The prophylaxis can be mechanical or pharmacological.\nProphylaxis for DVT\xa0\nMechanical\xa0Prophylaxis include :\xa0\nEarly ambulation\xa0\n\nIt is the simplest method of prophylaxis\nIt acts by activating the calf pump mechanism\n\nPneumatic compression devices\n\nIt is the most common method of prophylaxis\nPneumatic compresses prevents the stasis by periodically compressing the calves.\n\nPharmacological\xa0Prophylaxis include\n\nUse of unfractionated heparin -\xa0Now being replaced by fractionated low molecular weight heparin\nUse of fractionated low molecular -\xa0Better efficacy than unfractionated heparin\nweight heparin -\xa0No laboratory monitoring is necessary\n\nComparison 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.\xa0 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.\nIn 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.', 'role': 'assistant'}]