investigations

Last reviewed 01/2018

A number of imaging techniques are available for the assessment of AAA.

• ultrasonography
• non invasive, low cost method with the sensitivity and specificity close to 100%
• measures the size of the aorta in longitudinal as well as in anteroposterior and transverse directions
• modality of choice for initial assessment, follow up, screening and surveillance
• should have a low threshold for arranging abdominal ultrasonography in patients at risk. 
• CT
• can visualise
• the proximal neck (the transition between the normal and aneurysmal aorta)
• any extensions of the aneurysm (to the iliac areries)
• patency of visceral arteries
• the presence of blood within the thrombus (crescent sign) - is considered a predictive marker of imminent rupture
• helical CT and CT angiography can provide additional anatomical details - useful if an endovascular procedure is considered
• resonance angiography (MRA)
• safer than conventional arteriography since it does not use nephrotoxic contrast material (1,2)
• plain radiography
• calcified aneurysmal wall may be seen in some cases

In addition, baseline laboratory assessment for cardiovascular risk factors could be carried as well.  

In the acute presentation of a leaking or ruptured abdominal aortic aneurysm, the admitting doctor should move immediately from the clinical diagnosis to the emergency management

Reference:

• (1) Metcalfe D, Holt PJ, Thompson MM. The management of abdominal aortic aneurysms. BMJ. 2011;342:d1384.
• (2) Sakalihasan N, Limet R, Defawe OD. Abdominal aortic aneurysm. Lancet. 2005;365(9470):1577-89