Abdominal Aortic Aneurysm (AAA)

Question 1

Define AAA summarising its aetiology/risk factors

Answer 1

Definition: A localised enlargement of abdominal aorta such that the diameter is >3cm or >
50% larger than normal diameter (normal is usually around 2cm)

Aetiology/risk factors:
- There are NO specific identifiable causes
- Risk factors:
• Severe atherosclerotic damage to aortic wall
• Family history
• Male
• Age
• Hypertension
• Smoking
• Hyperlipidaemia
• Connective tissue disorders: Marfan ‘s Syndome, Ehlers-Danlos syndrome
• Inflammatory disorders: Behcet’s disease, Takayasu’s arteritis

Question 2

Describe the history/presenting symptoms of AAA

Answer 2

• Unruptured
  • No symptoms
  • Discovered incidentally
  • May have pain in the back, abdomen, loin or groin

- Ruptured
  • Pain in the abdomen, back or loin
  • Pain may be sudden or severe
  • Syncope
  • Shock: Degree of shock depend on site of rupture and whether it is contained

Question 3

What are the signs of AAA upon physical examination?

Answer 3

• Pulsatile and Laterally expansile mass on bimanual palpation of the abdominal aorta
• Abdominal bruit
• Retroperitoneal haemorrhage can cause Grey-Turner’s sign

Question 4

What investigations are used to identify AAA? How would you interpret the results?

Answer 4

1st line investigations
- Ultrasound- Can detect aneurysm but cannot tell whether it is leaking or not.

Other investigations
- Bloods:
• FBC (leukocytosis, anaemia ), clotting screen, renal function and liver function
• Cross match if surgery is planned

• Scans:
  • CT with contrast- Can show whether an aneurysm has ruptured
  • MRI angiography

All scans show abdominal aortic dilation of >1.5 times the expected anterior-posterior diameter of that segment, given the patient’s sex and body size; the most commonly adopted threshold is a diameter of 3 cm or more