Which diameter defines an abdominal aortic aneurysm?

Which diameter defines an abdominal aortic aneurysm?

• A. Diameter > 3 cm
• B. Diameter > 5 cm
• C. Diameter < 2 cm
• D. Diameter = 3 cm

Answer: (A)

An abdominal aortic aneurysm is defined when the abdominal aorta’s diameter is greater than 3 cm. The normal infrarenal aorta is about 2 cm or less, so exceeding 3 cm represents abnormal dilation on imaging. This threshold is used because it reliably distinguishes aneurysmal dilation and correlates with increased risk of rupture as the vessel enlarges. Diameters around 5 cm indicate a higher rupture risk and often prompt surgical planning, but the diagnostic definition remains a diameter greater than 3 cm. A diameter exactly at 3 cm sits at the boundary and is not considered aneurysmal by definition.

An abdominal aortic aneurysm is defined when the abdominal aorta’s diameter is greater than 3 cm. The normal infrarenal aorta is about 2 cm or less, so exceeding 3 cm represents abnormal dilation on imaging. This threshold is used because it reliably distinguishes aneurysmal dilation and correlates with increased risk of rupture as the vessel enlarges. Diameters around 5 cm indicate a higher rupture risk and often prompt surgical planning, but the diagnostic definition remains a diameter greater than 3 cm. A diameter exactly at 3 cm sits at the boundary and is not considered aneurysmal by definition.