The surgeon's preoperative assessment of a patient has identified that the patient is at a high risk for venous thromboembolism. Once the patient is admitted to the postsurgical unit, what intervention should the nurse prioritize to reduce the patient's risk of developing this complication?

Choice A reason: The incentive spirometer is primarily used to prevent pulmonary complications such as atelectasis and pneumonia by promoting deep breathing and alveolar expansion. While it is a critical postoperative intervention, it has no direct physiological effect on the prevention of venous stasis or thrombus formation. Choice B reason: Early ambulation is the most effective nursing intervention to prevent venous thromboembolism (VTE). Walking activates the "calf muscle pump," which compresses the deep veins and facilitates venous return to the heart, thereby preventing the stasis of blood that leads to the formation of a thrombus. Choice C reason: Encouraging oral fluids helps maintain hydration and prevents hemoconcentration, which can contribute to a hypercoagulable state. However, hydration alone is insufficient to prevent VTE in a high-risk surgical patient compared to the mechanical benefits of active movement and leg exercises. Choice D reason: Passive range-of-motion exercises are helpful for patients who are completely immobile, but they are less effective than active ambulation. Furthermore, performing them only every 8 hours is infrequent for a high-risk patient; mechanical prophylaxis needs to be much more frequent to effectively counteract venous stasis.