A “pulmonary embolism” is, frankly speaking, a blockage of an artery in the lung by an embolus. So where exactly does the blood clot come from? To understand this problem, we have to start from our blood circulation. Just like a river, human blood flows in the blood vessels 24 hours a day. But when the river is flowing, it will take away stones, sediment, debris and then gradually accumulate in a certain place! Of course, there is no such thing as rocks or sediment in the blood vessels, but human blood contains many substances such as platelets that can have a “pro-coagulant” effect. When a person undergoes a series of “surgical procedures” on the lower extremities, the endothelium of the veins in the lower extremities is inevitably damaged. –causing thrombosis. Unlike “water”, “sticky” substances are difficult to flow. When a person takes certain medications, such as “birth control pills” or other drugs that have a clotting effect, the body’s blood becomes “sticky” and the probability of a blood clot increases. The above two factors are related to “river repair” and “blood stickiness” respectively, while the third factor is “blood content”. Due to the lack of movement of the muscles of the lower limbs during prolonged lying, a large amount of blood accumulates in the “veins of the lower limbs”, which provides suitable conditions for the formation of blood clots in the long run. Such cases are common in clinical practice. Doctor’s tip: Look for the right cause and be prepared. Regardless of surgery or medication, and in daily life, you should communicate with your doctor for proper and reasonable activities to minimize the probability of “pulmonary embolism”.