Which patient symptom is most suggestive of a pulmonary embolus in a patient with leg swelling and pain?

The symptom that is most suggestive of a pulmonary embolus, particularly in the context of leg swelling and pain, is the combination of leg swelling and pain with palpation of deep veins. This presentation aligns with the classic signs of deep vein thrombosis (DVT), which is a common precursor to pulmonary embolism. When a blood clot forms in the deep veins of the legs, it can lead to both localized symptoms (swelling and pain) and a potential embolic event if the clot dislodges and travels to the pulmonary circulation.

While tachycardia, hemoptysis, and a history of cancer can be associated with pulmonary embolism, they are not as directly indicative of the condition when considered in conjunction with the specific symptoms of leg swelling and pain. Tachycardia may be a reaction to hypoxia or stress, hemoptysis could suggest a variety of lung issues, and a past history of cancer increases the risk for thrombosis but is not a direct symptom of an existing pulmonary embolism. Therefore, the presence of leg swelling and pain with deep vein palpation suggests the need for further evaluation for DVT, which directly points to the risk of pulmonary embolism.