What does a pulmonary embolism (PE) involve?

A pulmonary embolism (PE) primarily involves a blood clot that travels to the lungs and lodges in a pulmonary artery. This condition is critical because the blockage can significantly impede blood flow to lung tissue, potentially leading to serious complications like respiratory distress or even death if not treated promptly. The blood clot typically originates from deep veins in the legs or other parts of the body, a condition referred to as deep vein thrombosis.

In contrast, the other options describe different medical conditions. A viral infection in the lungs relates to illnesses like pneumonia or bronchitis, which are caused by pathogens rather than blood clots. Accumulation of fluid in the pleural space refers to pleural effusion, which is not directly connected to the clotting concerns of a PE. A chronic state of lung collapse describes conditions such as pneumothorax or atelectasis, which also do not involve blood clots in the pulmonary arteries. Understanding these distinctions is crucial for differentiating between various respiratory and circulatory issues.