Diagnosis of abdominal aortic aneurysm (AAA)

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)

Reference:

• (1) Keisler B, Carter C. Abdominal aortic aneurysm. Am Fam Physician. 2015;91(8):538-43.
• (2) Chaikof EL et al. The care of patients with an abdominal aortic aneurysm: the Society for Vascular Surgerypractice guidelines. J Vasc Surg. 2009;50(4 Suppl):S2-49
• (3) Metcalfe D, Holt PJ, Thompson MM. The management of abdominal aortic aneurysms. BMJ. 2011;342:d1384.