What is considered the most significant risk factor for developing a pulmonary embolism?

• A. Immobility
• B. Cancer
• C. Deep vein thrombosis
• D. Recent surgery

Answer: (C)

The most significant risk factor is a deep vein thrombosis. A pulmonary embolism almost always starts when a clot forms in the deep veins of the legs or pelvis and then travels to the lungs. So, having a DVT directly indicates a source that can embolize and cause a PE, making it the strongest predictor among risk factors.

Other factors like immobility, recent surgery, or cancer increase the likelihood of clot formation, but they do so by promoting conditions for clots to develop. The presence of a DVT already identifies a thrombus that can migrate to the lungs, which is why it’s considered the most significant risk factor.