Abdominal Aortic Aneurysm (AAA)

Exam Cram

• AAA: abdominal aorta aneurysm

• Enlargement of abdominal aorta

• Presentation: abdominal pain

• Investigations: imaging- USS or CT Angio

  • Screening abdo USS > 65yrs

• Management: (dictated by size): operation once > 5.5cm

Outline

Background 

Aneurysm is defined in a increase in diameter by more than 50cm. The aorta's diameter is normally 2cm, so > 3cm would be a AAA. 

Risk factors

• HTN

• Hypercholesterolaemia

• Aortic Dissection

• Smoking

• Elderly

• Male

• Caucasian

Rarer causes

• Syphillis

• HIV

• Connective tissue disorder: Ehlers Danlos syndrome (EDS)  , Marfan's Syndrome 

Diagnosis

Diagnostic criteria: 

• > 3cm diameter on imaging

History & examination:

• Incidental findings: asymptomatic

• Ruptured: 

  • • Acute abdominal pain

    • Peritonitic abdominal tenderness

Investigations

• Imaging

  • • USS / CT / MRI Angio 

Differentials

• Renal calculi

Management

Dimensions Size Management

• < 3cm: Normal Nil scanning

• 3-4.4cm: Small Yearly scan

• 4.5-5.4cm: Medium 3m scan

• 5.5cm> Large Referral to vascular specialist

Surgical Reg Notes

Screening (UK)

Men over 65yrs: once off ultrasound

• 1/1000: AAA > 5.5cm

• 1/250 screened will have an operation

• 1/40 not survive the operation

Prognosis

Enlargement rate: 0.2-0.3cm/ yr

Further management

• BP control

• May require stop driving

Indications for Surgery

1. AAA > 5.5cm

2. Rapidly expanding

3. Presence of peripheral arterial disease or aneurysm

References

1. Shaw PM, Loree J, Gibbons RC. Abdominal Aortic Aneurysm. [Updated 2024 Feb 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470237/ 

2. https://www.gov.uk/guidance/abdominal-aortic-aneurysm-screening-programme-overview