Shortness of breath associated with unilateral leg swelling is likely caused by?

Shortness of breath in conjunction with unilateral leg swelling often indicates a problem with blood flow or clotting, particularly in the presence of a Deep Vein Thrombosis (DVT). DVT can lead to a pulmonary embolism, where a clot travels to the lungs, causing respiratory symptoms like shortness of breath.

In this scenario, the swelling in the leg results from the accumulation of fluid due to a clot obstructing venous drainage. The unilateral nature of the swelling suggests that it is localized to one leg, which is typical in cases of DVT. When a clot from the leg moves to the lungs, it restricts blood flow, leading to chest discomfort and respiratory distress.

Other conditions such as congestive heart failure could cause leg swelling but typically would be accompanied by bilateral swelling and different patterns of respiratory distress. Chronic Obstructive Pulmonary Disease might result in shortness of breath but doesn’t directly correlate with unilateral swelling in the leg. Pneumonia primarily causes respiratory symptoms without the typical presentation of unilateral leg edema. Therefore, the combination of unilateral leg swelling and shortness of breath is most consistent with a DVT resulting in a pulmonary embolism.