Question

The most common cause of abdominal aortic aneurysm is:

• A. Atherosclerosis
• B. Trauma
• C. Syphilis
• D. Vasculitis

Hint:

Think older smoker with an infrarenal aorta worn down by the same plaque that clogs arteries.

Answer 1

The Correct Option is A

Step 1: An abdominal aortic aneurysm (AAA) is a permanent localised dilatation of the infrarenal aorta, occurring mostly in older men with cardiovascular risk factors.
Step 2: The dominant underlying process is degeneration of the aortic wall driven by atherosclerosis, with loss of elastin and smooth muscle and increased wall stress. Atherosclerosis is therefore the most common cause.
Step 3: Trauma (option B) causes pseudoaneurysms and is uncommon as a cause of a true AAA. Syphilis (option C) classically affects the ascending thoracic aorta, not the abdominal aorta. Vasculitis (option D) is a rare cause.
Step 4: The location (infrarenal abdominal aorta) and the typical risk profile (smoking, hypertension, hyperlipidaemia, age, male sex) all align with atherosclerotic degeneration.
Step 5: Hence the most common cause is atherosclerosis.
Answer: A. Atherosclerosis.