What action should a person take to prevent the development of a pulmonary embolism?

Pulmonary embolism (PE) most commonly results from deep vein thrombosis (DVT) where a clot breaks free and travels to the pulmonary vasculature. Increasing daily fluid consumption helps prevent PE by maintaining blood viscosity and reducing the risk of clot formation; dehydration causes blood to become more viscous and increases the likelihood of thrombus development. Adequate hydration is a straightforward preventive measure that supports venous blood flow and discourages stasis, one of the key components of Virchow's triad (stasis, hypercoagulability, and endothelial injury). Prolonged bed rest after surgery is actually a major risk factor for PE, not a preventive measure, because immobility promotes venous stasis and increases clotting risk. Ice packs on the legs would cause vasoconstriction and reduce blood flow, potentially worsening venous stasis rather than preventing clot formation. Starting oral contraceptive medication is also a risk factor for PE, particularly in women who smoke, because estrogen promotes a hypercoagulable state. Preventive strategies for PE include early mobilization after surgery, use of compression stockings, anticoagulant prophylaxis, and adequate hydration. Among the given options, increasing daily fluid consumption is the only action that actively reduces thrombus risk.