Abdominal aortic aneurysm: Difference between revisions

(Major update: POCUS sensitivity, permissive hypotension, REBOA, size-based rupture risk, USPSTF screening, surveillance guidelines, references with PMIDs)
(Strip excess bold text - keep only critical safety emphasis)
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==Background==
==Background==
*Focal dilation of the abdominal aorta to '''>50% of normal diameter''' (typically >3 cm)
*Focal dilation of the abdominal aorta to >50% of normal diameter (typically >3 cm)
*Most commonly '''infrarenal''' (95%)
*Most commonly infrarenal (95%)
*'''Ruptured AAA is a surgical emergency''' with overall mortality of '''65-85%''' (including prehospital deaths)
*'''Ruptured AAA is a surgical emergency''' with overall mortality of '''65-85%''' (including prehospital deaths)
*For those who reach OR, mortality is still '''40-50%'''
*For those who reach OR, mortality is still 40-50%
*Risk factors:
*Risk factors:
**Age '''> 65 years''', male sex (6:1 ratio), smoking (strongest modifiable risk)
**Age > 65 years, male sex (6:1 ratio), smoking (strongest modifiable risk)
**[[Hypertension]], family history, [[COPD]], peripheral vascular disease
**[[Hypertension]], family history, [[COPD]], peripheral vascular disease
**Connective tissue disorders (Marfan, Ehlers-Danlos)
**Connective tissue disorders (Marfan, Ehlers-Danlos)
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==Clinical Features==
==Clinical Features==
===Classic Triad of Ruptured AAA===
===Classic Triad of Ruptured AAA===
*'''Abdominal/back pain + hypotension + pulsatile abdominal mass'''
*Abdominal/back pain + hypotension + pulsatile abdominal mass
*Present in '''only ~50%''' of cases
*Present in only ~50% of cases


===Presentations===
===Presentations===
*'''Intact (unruptured) AAA''': usually asymptomatic or incidental finding
*Intact (unruptured) AAA: usually asymptomatic or incidental finding
*'''Symptomatic unruptured''': abdominal/back/flank pain (expanding aneurysm)
*Symptomatic unruptured: abdominal/back/flank pain (expanding aneurysm)
*'''Ruptured AAA''':
*Ruptured AAA:
**'''Sudden, severe abdominal or back pain''' (may radiate to groin, flank, or thigh)
**Sudden, severe abdominal or back pain (may radiate to groin, flank, or thigh)
**'''Hypotension''' / hemorrhagic [[shock]]
**Hypotension / hemorrhagic [[shock]]
**Pulsatile abdominal mass (difficult to palpate in obese or hypotensive patients)
**Pulsatile abdominal mass (difficult to palpate in obese or hypotensive patients)
**May present as '''syncope''' or [[cardiac arrest]]
**May present as syncope or [[cardiac arrest]]
*'''Contained rupture''': retroperitoneal hemorrhage may be temporarily tamponaded
*Contained rupture: retroperitoneal hemorrhage may be temporarily tamponaded
**Transient hemodynamic stability — '''do not be falsely reassured'''
**Transient hemodynamic stability — '''do not be falsely reassured'''
*'''Mimics''' many conditions: [[renal colic]], [[diverticulitis]], [[MI]], musculoskeletal back pain
*Mimics many conditions: [[renal colic]], [[diverticulitis]], [[MI]], musculoskeletal back pain


==Differential Diagnosis==
==Differential Diagnosis==
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==Evaluation==
==Evaluation==
===Bedside Ultrasound (First-Line in ED)===
===Bedside Ultrasound (First-Line in ED)===
*'''POCUS is the single most important test''' for unstable patients
*POCUS is the single most important test for unstable patients
*'''Sensitivity ~100%''' for detecting aneurysm >3 cm<ref>Tayal VS, et al. Emergency department sonographic measurement of aortic diameter. ''J Ultrasound Med''. 2003;22(12):1291-1294. PMID 14680900</ref>
*'''Sensitivity ~100%''' for detecting aneurysm >3 cm<ref>Tayal VS, et al. Emergency department sonographic measurement of aortic diameter. ''J Ultrasound Med''. 2003;22(12):1291-1294. PMID 14680900</ref>
*Measure outer wall to outer wall in '''transverse''' view
*Measure outer wall to outer wall in transverse view
*'''Cannot reliably detect rupture''' (free fluid may suggest it but absence does not exclude)
*Cannot reliably detect rupture (free fluid may suggest it but absence does not exclude)
*'''US identifies the aneurysm; CT identifies the rupture'''
*US identifies the aneurysm; CT identifies the rupture


===CT Angiography===
===CT Angiography===
*'''Gold standard for defining anatomy''' and surgical planning
*Gold standard for defining anatomy and surgical planning
*Identifies rupture, contained leak, extent, relation to renal arteries
*Identifies rupture, contained leak, extent, relation to renal arteries
*'''ONLY for hemodynamically STABLE patients'''
*ONLY for hemodynamically STABLE patients
*Sensitivity for rupture approaches 100%
*Sensitivity for rupture approaches 100%


===Labs===
===Labs===
*'''Type and crossmatch''' (at least 6 units PRBCs)
*Type and crossmatch (at least 6 units PRBCs)
*CBC, BMP, coagulation studies, lactate
*CBC, BMP, coagulation studies, lactate
*'''Do NOT delay resuscitation or imaging for labs'''
*'''Do NOT delay resuscitation or imaging for labs'''
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==Management==
==Management==
===Ruptured AAA===
===Ruptured AAA===
*'''Activate massive transfusion protocol'''
*Activate massive transfusion protocol
*'''Permissive hypotension''': target SBP '''70-90 mmHg'''
*Permissive hypotension: target SBP 70-90 mmHg
*'''Avoid aggressive crystalloid''' resuscitation; use blood products
*Avoid aggressive crystalloid resuscitation; use blood products
*Emergent '''vascular surgery consultation'''
*Emergent vascular surgery consultation
*'''Unstable patients go directly to OR''' (do NOT delay for CT)
*'''Unstable patients go directly to OR''' (do NOT delay for CT)
**EVAR if anatomy suitable and resources available
**EVAR if anatomy suitable and resources available
**Open surgical repair if EVAR not feasible
**Open surgical repair if EVAR not feasible
*'''If arrest''': consider '''REBOA''' or '''ED thoracotomy with aortic cross-clamp'''
*If arrest: consider REBOA or ED thoracotomy with aortic cross-clamp


===Symptomatic Unruptured AAA===
===Symptomatic Unruptured AAA===
*'''Urgent vascular surgery consultation'''
*Urgent vascular surgery consultation
*Blood pressure control: target SBP 100-120 mmHg
*Blood pressure control: target SBP 100-120 mmHg
*Admit for expedited repair
*Admit for expedited repair
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*4-5.4 cm: surveillance US every 6 months; vascular referral
*4-5.4 cm: surveillance US every 6 months; vascular referral
*>=5.5 cm: refer for elective repair
*>=5.5 cm: refer for elective repair
*'''USPSTF: one-time screening US''' for men 65-75 who have ever smoked
*USPSTF: one-time screening US for men 65-75 who have ever smoked


==Disposition==
==Disposition==
*'''Ruptured''': emergent OR / ICU
*Ruptured: emergent OR / ICU
*'''Symptomatic unruptured''': monitored bed, urgent vascular consult
*Symptomatic unruptured: monitored bed, urgent vascular consult
*'''Asymptomatic incidental''': outpatient vascular referral
*Asymptomatic incidental: outpatient vascular referral


==See Also==
==See Also==

Revision as of 09:23, 22 March 2026

Background

  • Focal dilation of the abdominal aorta to >50% of normal diameter (typically >3 cm)
  • Most commonly infrarenal (95%)
  • Ruptured AAA is a surgical emergency with overall mortality of 65-85% (including prehospital deaths)
  • For those who reach OR, mortality is still 40-50%
  • Risk factors:
    • Age > 65 years, male sex (6:1 ratio), smoking (strongest modifiable risk)
    • Hypertension, family history, COPD, peripheral vascular disease
    • Connective tissue disorders (Marfan, Ehlers-Danlos)
  • Risk of rupture increases with size:
    • <5 cm: ~1%/year
    • 5-6 cm: ~10%/year
    • >7 cm: ~30%/year

Clinical Features

Classic Triad of Ruptured AAA

  • Abdominal/back pain + hypotension + pulsatile abdominal mass
  • Present in only ~50% of cases

Presentations

  • Intact (unruptured) AAA: usually asymptomatic or incidental finding
  • Symptomatic unruptured: abdominal/back/flank pain (expanding aneurysm)
  • Ruptured AAA:
    • Sudden, severe abdominal or back pain (may radiate to groin, flank, or thigh)
    • Hypotension / hemorrhagic shock
    • Pulsatile abdominal mass (difficult to palpate in obese or hypotensive patients)
    • May present as syncope or cardiac arrest
  • Contained rupture: retroperitoneal hemorrhage may be temporarily tamponaded
    • Transient hemodynamic stability — do not be falsely reassured
  • Mimics many conditions: renal colic, diverticulitis, MI, musculoskeletal back pain

Differential Diagnosis

Template:Abdominal pain DDX

Evaluation

Bedside Ultrasound (First-Line in ED)

  • POCUS is the single most important test for unstable patients
  • Sensitivity ~100% for detecting aneurysm >3 cm[1]
  • Measure outer wall to outer wall in transverse view
  • Cannot reliably detect rupture (free fluid may suggest it but absence does not exclude)
  • US identifies the aneurysm; CT identifies the rupture

CT Angiography

  • Gold standard for defining anatomy and surgical planning
  • Identifies rupture, contained leak, extent, relation to renal arteries
  • ONLY for hemodynamically STABLE patients
  • Sensitivity for rupture approaches 100%

Labs

  • Type and crossmatch (at least 6 units PRBCs)
  • CBC, BMP, coagulation studies, lactate
  • Do NOT delay resuscitation or imaging for labs

Management

Ruptured AAA

  • Activate massive transfusion protocol
  • Permissive hypotension: target SBP 70-90 mmHg
  • Avoid aggressive crystalloid resuscitation; use blood products
  • Emergent vascular surgery consultation
  • Unstable patients go directly to OR (do NOT delay for CT)
    • EVAR if anatomy suitable and resources available
    • Open surgical repair if EVAR not feasible
  • If arrest: consider REBOA or ED thoracotomy with aortic cross-clamp

Symptomatic Unruptured AAA

  • Urgent vascular surgery consultation
  • Blood pressure control: target SBP 100-120 mmHg
  • Admit for expedited repair

Incidental Asymptomatic AAA

  • <4 cm: surveillance US every 12 months
  • 4-5.4 cm: surveillance US every 6 months; vascular referral
  • >=5.5 cm: refer for elective repair
  • USPSTF: one-time screening US for men 65-75 who have ever smoked

Disposition

  • Ruptured: emergent OR / ICU
  • Symptomatic unruptured: monitored bed, urgent vascular consult
  • Asymptomatic incidental: outpatient vascular referral

See Also

References

  1. ↑ Tayal VS, et al. Emergency department sonographic measurement of aortic diameter. J Ultrasound Med. 2003;22(12):1291-1294. PMID 14680900
  • Chaikof EL, et al. SVS practice guidelines for AAA. J Vasc Surg. 2018;67(1):2-77. PMID 29268916
  • Kent KC. Abdominal aortic aneurysms. N Engl J Med. 2014;371(22):2101-2108. PMID 25427112
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