Abdominal aortic aneurysm (AAA) - emergency department guide
This section summarises recognition, immediate ED management, investigations and safe transfer of patients with suspected or confirmed abdominal aortic aneurysm (AAA), emphasising points relevant to frontline practice and exam scenarios.
Recommendations align with NICE NG156, RCEM Best Practice for ruptured AAA (rAAA) and the NHS AAA Screening Programme. Where local protocols differ, follow local vascular and critical care advice and consultant‑to‑consultant discussion.
Overview
- An AAA is a focal dilatation of the abdominal aorta - conventionally an aortic diameter ≥ 3.0 cm or a
> 50% increase from baseline.
- Most AAAs are infra‑renal (≈ 90-95%) and may extend into the iliac arteries.
- Rupture is life‑threatening; early recognition, minimal delay and rapid transfer to a vascular centre are critical.
Who is at risk
- Increasing age.
- Male sex.
- Current or past smoking.
- Hypertension.
- Established atherosclerotic disease.
- Family history of AAA.
- Connective tissue disorders (for example, Marfan or Ehlers-Danlos) predispose to aneurysm formation but are uncommon causes of typical infra‑renal AAA.