A patient with successfully treated DVT remains at increased risk of DVT or PE for life and will need prophylaxis at times. Prophylaxis (with, for example, enoxaparin 40mg daily) should begin 12 hours before elective surgery. In orthopaedic surgery, it should be continued at this dose for three weeks after discharge from hospital2. Early remobilisation and compression stockings should be used routinely for all surgery. Intra-operative calf compression machines are often used in prolonged elective surgery. High-risk medical patients (eg, those likely to be inpatients for more than five days) should receive routine prophylaxis whether or not they have had a prior DVT. Seek advice if the patient has renal impairment because LMW heparins accumulate quickly in patients with moderate to severe renal failure. All women with previous DVT or artificial heart valves should receive daily heparin prophylaxis during pregnancy. Haematological review is recommended in those with diagnosed thrombophil...