123 Abdominal aortic aneurysm
Salient features
Examination
• Large expansile pulsation along the course of the abdominal aorta (examination for a pulsatile mass should be done by bimanual palpation of the supraumbilical area)
• Auscultate for bruit over the aneurysm and over the femoral pulses
• ‘Trash’ foot: digital infarcts in patient with easily palpable pulses (suggests either a popiliteal or abdominal aneursysmal source of emboli) (BMJ 2000;320:1193–6)
• Popliteal artery aneurysms often coexist and, in fact, their presence should prompt the physician to look for an abdominal aortic aneurysm.
• Ninety per cent of atherosclerotic abdominal aortic aneurysms present below the origin of the renal arteries and can involve the aortic bifurcation.
• The infrarenal aorta is normally 2 cm in diameter; when it exceeds 4 cm an aneurysm is said to exist.
• True arterial aneurysms are defined as 50% increase in the normal diameter of the vessel.
• Aneursymal process may affect any medium or large artery.
• The most commonly affected vessels are the aorta and iliac arteries, followed by popiliteal, femoral and carotid vessels.
Questions
Which investigations would you do to confirm your diagnosis?
• B mode ultrasonography of the abdomen: a simple, cheap and accurate screening test.
• Large aneurysms require angiography, but angiography may underestimate the size of lumen because of large clots.
• MRI is useful, particularly as it does not require administration of contrast.
