A pulmonary embolism can be caused by all of the following except:
A an aneurysm
B a blood clot
C an air bubble
D tissue
The correct answer and explanation is:
The correct answer is A. an aneurysm.
A pulmonary embolism (PE) occurs when a substance, typically a blood clot, travels to the lungs and blocks one of the pulmonary arteries. The condition can have serious consequences, including death, if not treated promptly. The most common causes of pulmonary embolism include:
- Blood Clot (B): This is the primary cause of most pulmonary embolisms. Clots often form in the deep veins of the legs, a condition known as deep vein thrombosis (DVT). These clots can dislodge and travel through the bloodstream, entering the right side of the heart and then being pumped into the lungs, where they can obstruct blood flow in the pulmonary arteries, causing a PE.
- Air Bubble (C): Air embolisms are another cause of pulmonary embolism, though much less common than blood clots. Air can enter the bloodstream through certain medical procedures, such as the insertion of a catheter or during surgery. When large air bubbles reach the pulmonary circulation, they can block blood vessels and create a life-threatening PE.
- Tissue (D): In rare cases, fragments of tissue, such as fat or bone marrow, can travel to the lungs and cause a pulmonary embolism. This can happen after a traumatic injury, such as fractures of long bones, where fat or bone marrow is released into the bloodstream.
However, an aneurysm is not a direct cause of pulmonary embolism. An aneurysm refers to an abnormal bulging or swelling in the wall of an artery due to weakness in the arterial wall. While an aneurysm can lead to other complications such as rupture or hemorrhage, it does not typically result in the formation of emboli that could travel to the lungs. Thus, option A is not associated with the cause of pulmonary embolism.
In summary, while blood clots, air bubbles, and tissue can all lead to pulmonary embolism, an aneurysm is not a cause. The primary risk factor for pulmonary embolism remains the formation of blood clots, particularly in individuals with conditions that predispose them to clot formation.