A 68-year-old man attends his first NHS abdominal aortic aneurysm screening ultrasound, which shows an infrarenal abdominal aortic aneurysm of 4.7 cm. He is asymptomatic, a current smoker of 30 pack-years, with hypertension on ramipril. He asks what happens next. What is the most appropriate management?
- AImmediate referral for elective aneurysm repair
- BAnnual ultrasound surveillance with smoking cessation and lifestyle advice
- CDischarge, as aneurysms under 5 cm never rupture
- DThree-monthly surveillance ultrasound with best medical therapy, referring to vascular surgery at 5.5 cm, rapid expansion or symptoms
- ECT angiography every six months in place of ultrasound surveillance, for greater accuracy and reproducibility of diameter measurement
Show answer and explanation
Correct answer: D
Screening-detected aneurysms are managed by size-stratified surveillance because trial evidence (UKSAT, ADAM) shows no survival benefit from repairing small aneurysms: below 5.5 cm, the annual rupture risk is lower than the mortality of intervention. UK surveillance intervals are annual for 3.0 to 4.4 cm and three-monthly for 4.5 to 5.4 cm, so his 4.7 cm aneurysm enters three-monthly ultrasound. The referral triggers are diameter of 5.5 cm or more, expansion above 1 cm per year, or symptoms (tenderness, back or abdominal pain attributable to the aneurysm) at any size. Equally important is best medical therapy: smoking cessation — the strongest modifiable driver of expansion and rupture — plus statin, antiplatelet and blood pressure treatment for the cardiovascular risk that kills more of these men than their aneurysms.
Why the others are wrong: A — repair at 4.7 cm exposes him to operative mortality with no survival gain. B — annual scanning is for 3.0 to 4.4 cm; at 4.7 cm the interval is three months. C — small aneurysms rupture rarely, not never, and they grow; discharge abandons him at the point surveillance matters. E — ultrasound is the surveillance tool: accurate for diameter, cheap and radiation-free; CT is for pre-operative planning or diagnostic uncertainty.
Key point: A 4.5 to 5.4 cm AAA gets three-monthly ultrasound surveillance with aggressive medical risk modification; repair is triggered at 5.5 cm, rapid expansion (>1 cm/year) or symptoms — not before.
Guidelines: NICE abdominal aortic aneurysm guidance (NG156) and NHS AAA Screening Programme: aneurysms of 4.5-5.4 cm have three-monthly surveillance ultrasound with best medical therapy; refer for repair at 5.5 cm, rapid growth, or symptoms.