Abdominal Aortic Aneurysm

Question 1

What is AAA?

Answer 1

This is a permanent pathological dilation of the aorta with a diameter >1.5 times the expected AP diameter of that segment, given the patient’s sex and body size.

Question 2

Where does most AAA occur?

Answer 2

More than 90% of aneurysms originate below the renal arteries.

Question 3

Causes of AAA

Answer 3

They arise from atherosclerotic disease mostly.

AAA exhibits significant heritability.

Question 4

Pathophysiology of AAA

Answer 4

Histologically, there is obliteration of collagen and elastin in the media and adventitia.
Smooth muscle cell loss resulting tapering of the medial wall, infiltration of lymphocytes and macrophages and neovascularisation.

Question 5

Classification of AAA

Answer 5

Congenital- medial degeneration occurs naturally with age. This is accelerated in patients with bicuspid aortic valves and Marfan syndrome.
Infectious- Rare aetiology. Staphylococcus and salmonella are the most common pathogens.
Inflammatory- Abnormal accumulation of macrophages and cytokines in diseased tissue.

Question 6

Typical patient with AAA

Answer 6

68 y/o man
Sudden sever abdominal and back pain
Pale with a HR of 124/min and BP of 90/60
Hands and feet are cold and clammy
NB: Most patients are usually asymptomatic and their AAA is detected incidently.

Question 7

Signs and symptoms of AAA

Answer 7

Palpable pulsatile abdominal mass (clinical examination only picks up 40-50% of AAA- difficult in obese people)
Abdominal, back and groin pain
Hypotension

Question 8

Risk factors of AAA

Answer 8

Cigarette smoking 
Hereditary/FHx 
Increased age 
Male sex (prevalence) 
Female sex (rupture) 
Congenital/connective tissue disorders

Question 9

Investigations of AAA

Answer 9

Abdominal ultrasound (adopted threshold is a diameter of >3cm)
CRP/ESR
FBC
Blood cultures

Question 10

Differentials of AAA

Answer 10

Diverticulitis 
Ureteric colic 
IBD 
IBS 
Biliary colic or acute cholangitis 
GI haemorrhage 
Perforated ulcer 
Appendicitis 
Ovarian torsion
Splanchnic artery aneurysms

Question 11

Screening in AAA

Answer 11

Offered to men when they turn 65
Ultrasound scan
Men aged 65 or over are most at risk of AAA

Question 12

What is the difference between transmitted & expansile pulsation?

Answer 12

Pulsatile/expansile- Fingers will move outward (a truly expansile mass likely to be an aneurysm originates from an artery)
Transmitted- Finger will move upwards. Pulsation disappear if you can move swelling away from aorta(patient in the knee-elbow position)