Monitoring

Surveillance of asymptomatic AAA

In the UK, the National Institute for Health and Care Excellence (NICE) recommends the following intervals for surveillance with aortic ultrasound:[42]​​​​

  • Annually if the AAA measures 3.0 to 4.4 cm 

  • Every 3 months if the AAA measures 4.5 to 5.4 cm.

A systematic review and meta-analysis of individual patient data concluded that surveillance intervals of 2 years for 3.0 to 4.4 cm AAAs, and 6 months for 4.5 to 5.4 cm AAAs, are safe and cost-effective.[95]​ The American College of Radiology recommends that colour duplex Doppler ultrasound, computed tomography (CT) of the abdomen and pelvis with contrast, and magnetic resonance angiography (MRA) are all appropriate imaging modalities for surveillance of patients with asymptomatic AAA; however, in the UK AAA surveillance is uniformly ultrasound-delivered.[263] 

Analysis of AAA growth and rupture rates indicated that, in order to maintain an AAA rupture risk <1%, an 8.5-year surveillance interval is required for men with baseline AAA diameter of 3.0 cm.[95] The corresponding estimated surveillance interval for men with an initial aneurysm diameter of 5.0 cm was 17 months. Despite having similar growth rates of small aneurysms, rupture rates were 4 times greater in women than in men.[95] Surveillance programmes and criteria for considering surgery need to be tailored for women with opportunistically detected AAA.

The European Society for Vascular Surgery (ESVS) recommends incorporation of subaneurysmal aortas (2.5 to 2.9 cm) into AAA surveillance recommendations because long-term cohort studies show that most subaneurysmal aortas eventually progress to an AAA of which a substantial proportion will reach the diameter threshold for consideration of repair.[3] Surveillance decisions should take into account life expectancy, suitability for future repair, and patient preferences.[3]

Surveillance post repair

NICE recommends that all patients who have had endovascular aneurysm repair (EVAR) should be enrolled into a surveillance imaging programme.[42] It also recommends that:[42]

  • Frequency of surveillance should be based on the patient’s risk of EVAR-related complications

  • Contrast-enhanced CT angiography (CTA) or colour duplex ultrasound may be used for assessing AAA diameter and EVAR device limb kinking

  • If an endoleak is suspected, contrast-enhanced CTA should be used as first-line imaging. However, if this is contraindicated, contrast-enhanced ultrasound may be used.

    • An endoleak should not be excluded using a negative colour duplex ultrasound alone following an EVAR.

The ESVS recommends that all patients should have CTA within 30 days of the initial repair.[3]​ For patients who have been stratified as being at low risk of complications (no endoleak, anatomy within manufacturer’s instruction for use [IFU], without high-risk features [proximal neck diameter <30 mm and angulation <60 degrees, and iliac diameter <20 mm], adequate overlap, and seal of 10 mm proximal and distal stent graft apposition to arterial wall), the ESVS recommends consideration for limited follow-up, with delayed imaging until 5 years after repair.[3] Patients stratified as being at high risk of complications (presence of type II endoleak, insufficient overlap or seal <10 mm, anatomy outside IFU, large proximal neck [>30 mm], ectatic iliac fixation zones [>20 mm], or extreme angulation [>60 degrees]) may be considered for yearly examinations with either CTA or duplex ultrasound.[3]​​

The US Society for Vascular Surgery recommends baseline surveillance with contrast-enhanced computed tomography (CT) and colour duplex ultrasound in the first month after EVAR.[76] If neither endoleak nor AAA enlargement is documented, imaging should be repeated at 12 months using either contrast-enhanced CT or colour duplex ultrasound imaging.[76]

Follow-up non-contrast CT imaging is recommended at 5-year intervals after open repair or EVAR.[76]

Women are at greater risk of postoperative complications (limb ischaemia, renal and cardiovascular complications) and mortality (in-hospital and 30-day) than men; strict long-term surveillance is essential in female patients undergoing AAA repair.[199][200]

Antibiotic prophylaxis of graft infection is required prior to bronchoscopy, gastrointestinal or genitourinary endoscopy, and any dental procedure that may lead to bleeding.[76]

Generalised sepsis, groin drainage, pseudoaneurysm formation, or ill-defined pain after open repair or EVAR should prompt evaluation of graft infection.[76] Gastrointestinal bleeding after open repair or EVAR should prompt evaluation of an aorto-enteric fistula.[76]

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