DEAR DOCTOR K: What is a pulmonary embolism?
DEAR READER: A pulmonary embolism occurs when a blood clot (called an embolus) suddenly blocks a blood vessel in the lung. A small pulmonary embolus can happen without causing any symptoms, but a large pulmonary embolus can suddenly threaten your life. To explain pulmonary embolism, let's begin with a refresher on the circulation of blood in our bodies. Blood carries nutrients (like oxygen and sugar) to the cells of our body and removes waste material from the cells. The blood circulates because of the pumping action of the heart.