When should a patient with an Abdominal Aortic Aneurysm (AAA) consult a vascular surgeon?

When to Consult Vascular Surgery for Abdominal Aortic Aneurysm (AAA)

Patients with AAA should be referred to vascular surgery when the aneurysm diameter reaches ≥5.5 cm in men or ≥5.0 cm in women, or when the aneurysm becomes symptomatic regardless of size. 1

Size-Based Referral Criteria

• Men with AAA ≥5.5 cm in diameter should be referred for vascular surgery evaluation for elective repair 1
• Women with AAA ≥5.0 cm in diameter should be referred for vascular surgery evaluation for elective repair 1
• Rapid growth of AAA (≥5 mm in 6 months or ≥10 mm per year) warrants vascular surgery referral regardless of absolute size 1
• Saccular aneurysms ≥4.5 cm may be considered for referral due to potentially higher rupture risk 1

Symptom-Based Referral Criteria

• Any symptomatic AAA requires immediate vascular surgery consultation regardless of size 1
• Symptoms suggesting possible AAA expansion or impending rupture include:
  • New-onset abdominal or back pain
  • Pulsatile abdominal mass with pain
  • Hypotension with known AAA (suggests rupture - medical emergency) 2

Surveillance Recommendations Before Referral

For AAAs below the threshold for surgical intervention, surveillance with ultrasound is recommended at the following intervals:

• AAA 3.0-3.9 cm: Every 3 years 1
• AAA 4.0-4.4 cm: Every 2 years for men; annually for women 1
• AAA 4.5-5.0 cm in men/4.5-4.9 cm in women: Every 6-12 months 1
• AAA 5.0-5.4 cm in men: Every 6 months (approaching threshold for intervention) 1

Special Populations Requiring Earlier Referral

• Women have a four-fold higher rupture risk at the same AAA diameter compared to men 1
• Patients with family history of AAA or other genetic risk factors may benefit from earlier referral 1
• Patients with multiple risk factors (smoking, hypertension, coronary artery disease) may warrant earlier referral 1

Pre-Referral Imaging Considerations

• Duplex ultrasound is recommended for initial surveillance of AAA 1
• CT angiography (CTA) should be obtained when:
  • AAA approaches surgical threshold (5.0-5.5 cm)
  • Ultrasound measurements are inadequate
  • Preparing for intervention planning 1
• MR angiography may be considered when CTA is contraindicated (e.g., renal insufficiency) 1

Common Pitfalls to Avoid

• Delaying referral for symptomatic AAAs regardless of size can lead to rupture and increased mortality 2
• Over-reliance on ultrasound measurements alone when approaching surgical thresholds (CT provides more accurate measurements) 1
• Failing to recognize that women have higher rupture risk at smaller diameters 1
• Not accounting for rapid growth rate which may necessitate earlier referral even if below size threshold 1
• Neglecting surveillance of smaller aneurysms, which should be monitored at appropriate intervals 1

Remember that the decision for surgical intervention balances rupture risk against operative risk. While 5.5 cm (men) and 5.0 cm (women) are standard thresholds, individual factors including age, comorbidities, and patient preference should be considered in consultation with vascular surgery 1, 3.