diagnosis of abdominal aortic aneurysm (AAA)

Last reviewed 01/2018

diagnosis

AAA is often diagnosed incidentally following imaging studies such as abdominal ultrasonography or CT (1).

A medical history is helpful in determining the patient's risk of developing an AAA.

  • enquiry should be made regarding any risk factors which may be present
    • family history of aneurysm
    • special consideration should be paid to the cardiovascular system in the functional enquiry (2).

On examination:

  • palpation of the abdomen
    • pulsatile mass should be palpated (palpation has not been reported to precipitate aortic rupture)
    • accuracy of palpating a pulsatile mass around the level of the umbilicus is greatly reduced by obesity, abdominal distention, and smaller aneurysm size
      • a small prospective study reported that
        • sensivitity of abdominal palpation by a doctor was 0.57 for detection of aneurysms less than 4 cm diameter and 0.98 for those over 5 cm
        • specificity for excluding an AAA was 0.64
    • the painful aneurysm will be tender to firm pressure but there will only be guarding and generalised tenderness if the aneurysm has leaked
    • aneurysm mass will be fusiform - unless the iliac arteries are involved when it will be bilobed - and expansile
    • the palpating hands are moved outwards instead of simply upwards which occurs in thin people with normal aortas
  • signs such as xanthelasma and arcus may be present. Attention should be paid towards detecting carotid disease as this may require investigation and treatment as a priority.
  • if the aneurysm has bled then there may be signs of blood loss e.g - flank ecchymosis (Grey Turner sign)
  • examine femoral/popliteal pulses and pedal (dorsalis pedis or posterior tibial) pulses to identify any associated aneurysm (femoral/popliteal) or occlusive disease (1,2,3)

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