Symptomatic and ruptured abdominal aortic aneurysm

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

A symptomatic unruptured AAA causes new abdominal or back pain or tenderness attributable to the aneurysm without demonstrated free rupture. A ruptured AAA allows blood to escape the aneurysm wall, commonly into the retroperitoneum, producing concealed haemorrhage and rapidly progressive shock. These states form an emergency spectrum: temporary tamponade can preserve blood pressure, and a patient who looks stable may deteriorate abruptly when the clot shifts or anaesthesia reduces sympathetic tone.

Do not demand the classic triad of pain, hypotension and a pulsatile abdominal mass. NICE says to consider rupture with new abdominal and/or back pain, cardiovascular collapse or loss of consciousness, with probability increased by an existing AAA, age over 60, current or previous smoking, and hypertension. Women have a higher rupture risk than men. Symptoms determine urgency: a painful 4.8 cm aneurysm needs immediate vascular assessment, whereas 5.5 cm is an elective threshold for an asymptomatic aneurysm.

The operational goal is definitive aortic control without avoidable delay. Obtain large-bore access, monitoring, blood samples and blood products while involving vascular surgery, anaesthesia, theatre and transfusion services. NICE advises a restrictive volume strategy during emergency transfer. ESVS 2024 similarly recommends permissive hypotension for rAAA, preferably resuscitating with blood products and accepting a conscious, stable patient at a lower pressure rather than chasing normal values; its suggested systolic range of 70–90 mmHg is European specialist guidance, not a numeric target stated by NICE, and individual perfusion needs still matter.

Key points

Treat new pain or collapse with suspected AAA as a vascular emergency.
Contact the regional vascular service immediately; after acceptance, leave the referring unit within 30 minutes.
Use restrictive resuscitation, prioritising blood components when needed; do not chase normal pressure before aortic control.
Use restrictive volume resuscitation during transfer; avoid vigorous crystalloid-driven normalisation before aortic control.
When resuscitation is required, activate major haemorrhage support and prioritise blood components through the local protocol.
Use immediate bedside ultrasound, but remember it detects AAA rather than reliably proving rupture.
Obtain thin-slice arterial CTA when the patient can tolerate imaging and repair is being evaluated.
A negative or non-diagnostic bedside scan does not end escalation when clinical suspicion remains.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Degenerative AAA

Most ruptures arise from degenerative infrarenal aneurysms in older adults, with smoking, hypertension, age, male sex and atherosclerotic disease marking increased prevalence or rupture risk.

Less common pathology

Inflammatory, infected, traumatic, anastomotic, saccular or connective-tissue-associated aneurysms may become symptomatic or rupture with different anatomical patterns and sometimes at smaller diameters.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Wall failure
Progressive extracellular matrix degradation, inflammation and loss of medial structural integrity allow aortic expansion until wall stress exceeds residual tensile strength.
2
Contained bleeding
Posterior or lateral rupture may initially be tamponaded by retroperitoneal tissues, preserving transient circulation while concealed blood loss and clot instability continue.
3
Shock spiral
Ongoing haemorrhage reduces preload and tissue perfusion; acidosis, hypothermia, calcium disturbance and coagulopathy then impair haemostasis and accelerate physiological collapse.
4
Pressure disruption
Aggressive restoration of normal pressure before proximal aortic control can increase bleeding, dislodge temporary clot and dilute coagulation factors.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Pain patternRed flag

Abrupt abdominal, flank or back pain may be severe, persistent and accompanied by diaphoresis, nausea or a sense of collapse.

Haemorrhagic physiologyRed flag

Tachycardia, hypotension, cool peripheries, confusion, syncope or oliguria indicate impaired perfusion from concealed bleeding.

Known aneurysmRed flag

Any new unexplained abdominal or back pain in a person with diagnosed AAA warrants immediate vascular discussion.

Examination limits

A pulsatile tender mass supports the diagnosis, but obesity, guarding or retroperitoneal bleeding may conceal it.

Contained ruptureRed flag

Preserved blood pressure does not exclude rupture because retroperitoneal tamponade can temporarily limit blood loss.

Aortocaval fistulaRed flag

Rupture into the vena cava may cause high-output heart failure, a continuous abdominal bruit and leg venous congestion.

Red flags requiring action

Sudden severe abdominal, flank or back pain with hypotension, syncope or collapse.
Known AAA with new persistent pain or abdominal tenderness, even below elective size thresholds.
A pulsatile abdominal mass with pain, shock or falling haemoglobin.
Unexplained collapse in an older current or former smoker, particularly with hypertension.
Failure to improve after repair, tense abdomen or oliguria suggesting abdominal compartment syndrome.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Immediate bedside aortic ultrasoundFirst step
Why
Identify an aneurysm during initial emergency assessment
Interpretation and limitations
An AAA supports immediate vascular escalation; ultrasound cannot reliably exclude rupture, and an unavailable or non-diagnostic scan must not delay discussion.
02
Thin-slice arterial CT angiography
Why
Confirm anatomy and plan open or endovascular repair
Interpretation and limitations
CTA shows rupture, proximal neck, branches and access vessels; use it when the patient can tolerate rapid scanning without delaying control.
03
Full blood count and group testing
Why
Assess anaemia and prepare compatible blood components rapidly
Interpretation and limitations
Early haemoglobin may be deceptively normal in acute haemorrhage; serial physiology and bleeding rate matter more than one value.
04
Coagulation screen and fibrinogen
Why
Detect and guide correction of haemorrhage-associated coagulopathy
Interpretation and limitations
Interpret dynamically with local major haemorrhage testing; dilution, consumption, hypothermia and acidosis can worsen clotting.
05
Renal function and blood gas
Why
Assess perfusion, metabolic stress and contrast-related planning constraints
Interpretation and limitations
Lactate and acidosis support shock severity but must never become prerequisites for vascular transfer or operative decision-making.
06
Electrocardiogram
Why
Identify concurrent ischaemia or arrhythmia during resuscitation
Interpretation and limitations
Abnormalities influence peri-operative management but should not divert attention from controlling suspected aortic haemorrhage.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Renal colic

Severe flank-to-groin pain and haematuria suggest ureteric obstruction, but shock, older age or known AAA require exclusion of rupture before reassurance.

Acute coronary syndrome

Inferior myocardial infarction can cause epigastric pain, sweating and hypotension; ECG findings do not exclude concurrent or alternative catastrophic aortic bleeding.

Mesenteric ischaemia

Severe pain out of proportion and metabolic acidosis may indicate intestinal ischaemia, while a ruptured aneurysm can also cause secondary bowel hypoperfusion.

Aortic dissection

Abrupt chest or back pain, pulse deficits and malperfusion suggest dissection; CTA defines the aortic pathology when circulation allows.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Emergency pathwayImmediate stabilisation and transferFirst stepSuspected symptomatic or ruptured AAA in any acute setting

1Call the regional vascular service immediately while starting monitored ABC resuscitation.
2Secure large-bore intravenous access, send urgent bloods and activate major haemorrhage support when bleeding is likely.
3EscalationUse bedside ultrasound promptly, but continue escalation if it is unavailable or non-diagnostic.
4DefinitiveApply restrictive volume resuscitation and avoid delaying definitive aortic control to normalise blood pressure.
5When the vascular service accepts transfer, organise departure from the referring unit within 30 minutes.

02Imaging pathwayCTA when tolerableThe patient can undergo a brief scan while repair is being evaluated

1Continue vascular, anaesthetic, theatre and transfusion mobilisation during imaging.
2Acquire arterial-phase thoraco-abdominal and access-vessel anatomy suitable for operative planning.
3Move directly to the agreed EVAR or open repair pathway after image review.
4If deterioration makes scanning unsafe, prioritise immediate operative control under the vascular team.

03Definitive pathwayRupture repair decisionDefinitiveRuptured infrarenal AAA is confirmed and intervention remains appropriate

1Assess standard EVAR anatomical feasibility without delaying haemorrhage control.
2In UK NICE guidance consider EVAR or open repair, applying its age-and-sex benefit statements and anatomy.
3Use open repair when standard EVAR is unsuitable or offers the better individual balance.
4Do not deny repair solely because of advanced age or a prognostic score.

04After repairEarly complication searchPhysiology fails to improve after open repair or EVAR

1Reassess haemorrhage, cardiac function, limb perfusion and graft-related technical problems.
2Measure intra-abdominal pressure when abdominal compartment syndrome is suspected.
3Evaluate bowel ischaemia promptly when pain, acidosis or bloody diarrhoea raises concern.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Exsanguination

Loss of retroperitoneal tamponade may cause sudden uncontrolled intraperitoneal haemorrhage, profound shock, cardiac arrest and death before definitive control.

Abdominal compartment syndrome

Resuscitation, retroperitoneal haematoma and visceral oedema can raise intra-abdominal pressure after either EVAR or open repair, impairing renal, respiratory and circulatory function.

Bowel ischaemia

Hypoperfusion, embolisation or interruption of mesenteric and pelvic collateral flow may produce colonic ischaemia, acidosis, abdominal pain or bloody diarrhoea after repair.

Limb and renal injury

Shock, embolisation, graft-limb occlusion or renal ischaemia can cause acute kidney injury or lower-limb ischaemia requiring rapid recognition.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Continuously monitor consciousness, pulse, blood pressure, oxygenation, temperature and urine output.
Trend haemoglobin, lactate, base deficit, coagulation and fibrinogen without delaying aortic control.
Record vascular acceptance time, transfer decision time and departure time against the 30-minute standard.
After repair, monitor abdominal pressure, renal function, limb perfusion, bowel viability and ongoing bleeding.
Use active warming and reassess calcium and coagulation during major transfusion according to the local protocol.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Ultrasound limitation

Bedside ultrasound answers whether an aneurysm is present; retroperitoneal rupture may be invisible, so it cannot safely rule out rupture in a suspicious presentation.

Permissive hypotension population

NICE applies restrictive volume resuscitation to suspected ruptured or symptomatic AAA during emergency transfer; ESVS provides rAAA-specific European specialist detail and a conscious-patient pressure range.

Blood before clear fluid

ESVS advises that resuscitation efforts should preferably use blood products, supporting early major-haemorrhage activation and avoidance of large crystalloid volumes that dilute clotting factors.

Selection restraint

NICE advises against using any single symptom, sign, patient factor or risk score alone to decide suitability for ruptured AAA repair.

Rupture technique scope

NICE says EVAR benefits most people, especially men over 70 and women, while open repair may balance benefits better in men under 70; ESVS recommends EVAR first when anatomy is suitable.

11Common pitfallsFrequent interpretation and management errors.

01
Waiting for hypotension or the complete classic triad misses contained rupture.
02
Using 5.5 cm as an emergency gate delays treatment of a symptomatic smaller aneurysm.
03
Giving large crystalloid boluses to normalise pressure can disrupt tamponade and worsen coagulopathy.
04
Letting a non-diagnostic ultrasound postpone vascular discussion mistakes a limited test for an exclusion test.
05
Sending an unstable patient through prolonged investigations sacrifices time to definitive aortic control.
06
Applying ESVS numeric pressure advice as a rigid UK target ignores consciousness, perfusion and NICE wording.

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