Pulmonary embolism (PE) is a blockage in one or more pulmonary arteries in the lungs, usually caused by blood clots that travel from the legs (deep vein thrombosis). It is a critical condition that can lead to respiratory failure, cardiovascular collapse, or death if not promptly diagnosed and treated. A key association is the presence of risk factors such as prolonged immobility, recent surgery, or malignancy, which significantly increase the likelihood of developing PE.