Abdominal Aortic Aneurysm (AAA)

Question 1

What is the definition of an AAA?

Answer 1

A localised enlargement of the abdominal aorta such that the diameter is > 3 cm or > 50% larger than normal diameter.

NOTE: normal diameter of the aorta = 2 cm

Question 2

What is the aetiology of an AAA?

Answer 2

There are NO specific identifiable causes

Question 3

What are the risk factors of an AAA?

Answer 3

Severe atherosclerotic damage to aortic wall

Family history

Smoking

Male

Age

Hypertension

Hyperlipidaemia

Connective tissue disorders: Marfan’s syndrome, Ehlers-Danlos syndrome

Inflammatory disorders: Behcet’s disease, Takayasu’s arteritis

Question 4

What are the presenting symptoms of an AAA?

Answer 4

Unruptured

• NO SYMPTOMS
• Usually an incidental finding
• 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  
NOTE: degree of shock depends on site of rupture and whether it is contained

Question 5

What are the signs of an AAA upon physical examination?

Answer 5

Pulsatile and laterally expansile mass on bimanual palpation of the abdominal aorta

Abdominal bruit

Retroperitoneal haemorrhage can cause Grey-Turner’s sign

Question 6

What are the appropriate investigations for an AAA?

Answer 6

Bloods

• FBC, clotting screen, renal function and liver function
• Cross-match if surgery is planned

Scans

• Ultrasound - can detect aneurysm but CANNOT tell whether it is leaking or not
• CT with contrast - can show whether an aneurysm has ruptured
• MRI angiography