What abdominal aortic diameter is diagnostic for AAA? At what size is repair considered?

• A. Diagnostic: 3 cm; Repair: 5.5 cm
• B. Diagnostic: 4 cm; Repair: 6 cm
• C. Diagnostic: 2 cm; Repair: 5 cm
• D. Diagnostic: 3 cm; Repair: 4.5 cm

Answer: (A)

Abdominal aortic aneurysm management hinges on size: an infrarenal aorta measuring 3 cm or more is generally considered an aneurysm, because that diameter is about 50% larger than normal and carries rising rupture risk as it enlarges. Elective repair is usually recommended when the aneurysm reaches about 5.5 cm in diameter, since at that size the risk of rupture begins to outweigh the risks of surgery. Exceptions exist, such as rapidly enlarging aneurysms (growth of about 0.5 cm in six months) or symptomatic aneurysms, which warrant repair regardless of size.

So the diagnostic threshold is 3 cm, and the repair threshold is 5.5 cm. The other options propose thresholds that don’t match standard practice: a diagnostic threshold of 4 cm would miss many aneurysms defined at 3 cm, and repair thresholds of 4.5 cm (or 6 cm with the given wording) are not the conventional cutoffs used in routine guidelines.