Abdominal Aortic Aneurysm

Question 1

Define AAA

Answer 1

o Abdominal aortic aneurysm (AAA) is a permanent pathological dilation of the aorta with a diameter >1.5 times the expected anteroposterior (AP) diameter of that segment, given the patient’s sex and body size. [1] [2] The most commonly adopted threshold is a diameter of 3 cm or more. [3] More than 90% of aneurysms originate below the renal arteries.

Question 2

What are the 3 types of AAA?

Answer 2

o Congenital – degeneration accelerated in patients with bicuspid aortic valves and Marfan syndrome
o Infectious – rare, staph and salmonella most common. Chlamydia pneumoniae.
o Inflammatory – abnormal accumulation of macrophages, cytokines. Fibrosis, thickened walls and dense adhesions.

Question 3

What are the risk factors?

Answer 3

o Severe atherosclerotic damage to aortic wall
o Family history
o Smoking (most important)
o Male for prevalence, female for rupture
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

Question 4

Epidemiology

Answer 4

• Admissions for ruptured AAA fell from 18.6 to 13.5 per 100,000 in all age groups. The reduction in mortality and admissions has been attributed to the fall in smoking prevalence and the rise in elective AAA repair in older age groups.

Question 5

What are the presenting symptoms?

Answer 5

•	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, back or loin 
o	Pain may be sudden or severe 
o	Hypotension 
o	Syncope
o	Shock 
•	NOTE: degree of shock depends on site of rupture and whether it is contained

Question 6

What are the signs?

Answer 6

• Pulsatile and laterally expansile mass on bimanual palpation of the abdominal aorta (very hard, shown to be sensitive to those with AAA>5cm)
• Abdominal bruit
• Retroperitoneal haemorrhage can cause Grey-Turner’s sign

Question 7

What are the 1st line investigations?

Answer 7

Ultrasound

Question 8

What are the investigations to consider?

Answer 8

o Bloods – ESR/CRP (suggests inflammatory AAA), FBC (leucocytosis and relative anaemia + positive blood cultures suggest infective AAA)

o CT with contrast - can show whether an aneurysm has ruptured

o MRI angiography – preoperative strategy if allergic to contrast