Abdominal aortic aneurysm

Question 1

Define:

Answer 1

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

Question 2

Aetiology:

Answer 2

• There are NO specific identifiable causes
• Unruptured aneurysms occur due to degeneration of elastic lamellae and smooth muscle loss.

Ruptured AAAs can leak into retroperitoneal space (relatively haemodynamically stable) or intraperitoneal space (likely to result in shock)

Question 3

Epidemiology:

Answer 3

• Ruptured AAA:125 deaths per million in ages 55-59
• AAA screening programme being introduced in UK – all males >65 – ultrasound scan
• Unruptured AAA: 3% of >50 yrs, male: female ratio 3:1

Question 4

Symptoms:

Answer 4

• Unruptured
o NO SYMPTOMS
o Usually an incidental finding
o May have pain in the back, abdomen, loin or groin

RUPTURED
o	Pain in the abdomen – intermittent or continuous; radiates to back, iliac fossae or groin
o	Pain may be sudden or severe 
o	Syncope – low blood pressure
o	Shock

Question 5

Signs:

Answer 5

• Pulsatile and laterally expansile mass on bimanual palpation of the abdominal aorta
• Abdominal bruit
• Retroperitoneal haemorrhage can cause Grey-Turner’s sign (bruising in the flank area)
• Hypotension, tachycardia

Question 6

Investigations:

Answer 6

• Bloods
o FBC, clotting screen, renal function and liver function
o Cross-match if surgery is planned
• Scans
o Doppler Ultrasound - can detect aneurysm but CANNOT tell whether it is leaking or not
o CT with contrast - can show whether an aneurysm has ruptured
o MRI angiography

Management done in women if 5cm and in men if 5.5cm

Question 7

Difference between true and false aneurysm:

Answer 7

• A true aneurysm is an abnormal dilatation involving all layers of the arterial wall.
These can be fusiform (most AAAs) or sac-like

False aneurysms (pseudoaneurysms) involve a collection of blood in the outer layer only (adventitia) which communicates with the lumen e.g. after trauma.

Question 8

Risk factors:

Answer 8

o Severe atherosclerotic damage to aortic wall
o Family history
o Smoking
o Male
o Age
o Hypertension
o Hyperlipidaemia
o Connective tissue disorders: Marfan’s syndrome, Ehlers-Danlos syndrome
o Inflammatory disorders: Behcet’s disease, Takayasu’s arteritis