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Abdominal aortic aneurysm (AAA)
An abdominal aortic aneurysm is a dilatation of 3 cm or more; a small aneurysm is followed by ultrasound with risk-factor treatment, and repair is done when the diameter reaches 5.5 cm in men (5.0 in women), when it grows quickly or when it causes symptoms — and a ruptured aneurysm in an unstable patient goes straight to theatre.
Why it matters in the exam
AAA questions cover four topics. The first is risk factors and screening: a man over 65, smoking (the strongest risk factor), family history — and a one-off abdominal ultrasound for men at age 65. The second is surveillance by diameter: the larger the aneurysm, the shorter the interval between scans. The third is the threshold for repair: 5.5 cm in men, 5.0 in women, growth of more than 1 cm a year, or a tender, symptomatic aneurysm.
The fourth and most dramatic topic is rupture: sudden pain in the abdomen, back or flank, hypotension and a pulsatile mass. In an unstable patient with a known aneurysm or a pulsatile mass, no time is wasted on CT — the patient goes straight to theatre, with restricted fluids and a controlled low blood pressure. In a stable patient CT angiography is done, and endovascular repair (EVAR) is preferred when the anatomy is suitable. Candidates are also asked about EVAR versus open repair (lower early mortality versus lifelong imaging surveillance), leakage around the graft (endoleak), and ischaemia of the left colon after repair.
Key points
- Aneurysm = 3 cm or more; ultrasound screening for men at age 65.
- Surveillance: 3.0–3.9 cm every 3 years; 4.0–4.9 cm every year; 5.0–5.4 cm every 3–6 months.
- Repair: 5.5 cm in men, 5.0 in women, growth over 1 cm a year or symptoms.
- Rupture in an unstable patient — straight to theatre with controlled low blood pressure; stable — CT angiography.
- EVAR — lower early mortality, but lifelong imaging surveillance.
Summary table
| Diameter or situation | Surveillance | Action |
|---|---|---|
| 3.0–3.9 cm | Ultrasound every 3 years | Stop smoking, statin, treat hypertension |
| 4.0–4.9 cm | Ultrasound every year | As above |
| 5.0–5.4 cm | Ultrasound every 3–6 months | In women — consider repair from 5.0 cm |
| 5.5 cm or more in men, growth over 1 cm a year, or symptoms | — | Repair: EVAR when the anatomy is suitable, or open surgery |
| Rupture — unstable | — | Straight to theatre; restricted fluids and controlled low blood pressure |
| Rupture — stable | — | CT angiography; EVAR when possible |
In the full version for subscribers
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- 5 review cards
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The full version is open to subscribers of: Medical licensing exam (IMLE), General surgery, Vascular surgery, Emergency medicine, Family medicine, Geriatrics.
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Sources
- ESVS Clinical Practice Guidelines on the Management of Abdominal Aorto-iliac Artery Aneurysms, 2024 — Screening, surveillance, thresholds for repair and ruptured aneurysm
- SVS practice guidelines on the care of patients with an abdominal aortic aneurysm, 2018 — Surveillance intervals and EVAR versus open repair
- Sabiston Textbook of Surgery, 21st edition (2022) — Aneurysmal Vascular Disease
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.