Synopsis
Choose and interpret ultrasound, CT, MRI and echocardiography across screening, surveillance, repair planning and suspected acute aortic syndromes without delaying emergency care.
- Ultrasound is the practical test for detecting and surveilling infrarenal abdominal aortic aneurysm, but it does not map the whole thoracic aorta.
- Report abdominal aortic ultrasound using the stated measurement convention; NICE specifies inner-to-inner maximum anterior-posterior diameter for AAA decisions.
- Contrast CT angiography rapidly maps the entire aorta, branch vessels, rupture signs and repair anatomy, making it central in suspected acute aortic syndrome.
Key red flags
New abdominal or back pain with cardiovascular collapse, syncope or a known abdominal aortic aneurysm requires immediate consideration of rupture and bedside aortic ultrasound.
Abrupt maximal-at-onset chest or back pain with a pulse deficit, inter-arm pressure difference, focal neurological deficit, hypotension or a new aortic regurgitation murmur raises acute aortic syndrome risk.
Pericardial effusion, haemopericardium, mediastinal haematoma, pleural blood or contrast leak on imaging suggests life-threatening complication and requires direct emergency communication.
Renal, mesenteric, spinal, coronary or limb malperfusion may dominate the presentation; imaging must evaluate branch-vessel involvement as well as the aortic lumen.
A symptomatic aneurysm is clinically urgent even when its diameter is below a usual elective repair threshold.
An intimal flap divides contrast flow into true and false lumens. Identify the most proximal involved segment, distal extent, branch origins, lumen thrombosis and signs of malperfusion or rupture.
Stanford type A acute dissection involves the ascending aorta regardless of the entry-tear site and requires urgent cardiothoracic or aortic surgical assessment. Type B has no ascending-aorta involvement; imaging must identify rupture, malperfusion, rapid expansion and other complications that prompt urgent specialist intervention rather than uncomplicated medical surveillance alone.
Non-contrast CT may show crescentic or circumferential high attenuation within the wall without a typical flowing false lumen. Contrast imaging then assesses ulcer-like projections, extent and complications.
Contrast extends beyond the expected intimal surface into an atherosclerotic wall, sometimes with adjacent haematoma or pseudoaneurysm. Symptoms, depth, progression and rupture features determine urgency with specialist input.
Periaortic haematoma, retroperitoneal blood, haemothorax, haemopericardium, active contrast extravasation or loss of normal tissue planes support rupture. Absence of active leak does not exclude contained rupture.
Post-EVAR imaging assesses sac size, device position, limb patency, kinking, migration and endoleak. A negative routine colour duplex examination alone does not exclude every endoleak when suspicion persists.
Investigation priorities
Detect and surveil abdominal aortic aneurysm and provide an immediate bedside answer in suspected rupture.
Provide the recommended initial diagnostic imaging in most haemodynamically stable patients and map dissection, aneurysm, branch vessels, rupture signs and repair anatomy.
Management branches
Abrupt severe pain or collapse is accompanied by high-risk aortic history, examination findings or organ malperfusion.
- Assess haemodynamic stability, neurological and limb perfusion, pulses, bilateral arm pressures and features of rupture while resuscitation begins.
- Contact the aortic or vascular team early. In most haemodynamically stable patients with suspected acute aortic syndrome, obtain urgent CT angiography as the initial diagnostic imaging; use TEE or MRI when stability, contrast risk, access or availability makes an alternative more appropriate.