Pulmonary embolism is a serious medical condition that occurs when a blood clot blocks one or more arteries in the lungs. This blockage can prevent blood from reaching lung tissue, leading to reduced oxygen levels in the body. Common causes include deep vein thrombosis (DVT), where clots form in the legs and travel to the lungs. Symptoms of pulmonary embolism may include sudden shortness of breath, chest pain, and coughing up blood. It is a medical emergency that requires prompt treatment, which may involve medications to dissolve clots or procedures to remove them. Early diagnosis is crucial for improving outcomes.