What are the symptoms of an abdominal aortic aneurysm (AAA)?

Symptoms of Abdominal Aortic Aneurysm

Most abdominal aortic aneurysms remain completely asymptomatic until rupture occurs, with approximately two-thirds discovered incidentally on imaging performed for unrelated reasons. 1

Asymptomatic Presentation (Most Common)

• The majority of AAAs produce no symptoms whatsoever and are detected as incidental findings on ultrasound, CT, or other abdominal imaging studies. 1, 2
• Large unruptured aneurysms are frequently asymptomatic despite significant size, often found incidentally on physical examination or imaging. 3
• AAAs are typically asymptomatic until catastrophic rupture occurs. 4

Symptomatic Presentation (Indicates Impending or Actual Rupture)

Classic Triad (Present in Only 50% of Cases)

• Acute back pain, pulsatile abdominal mass, and hypotension constitute the classic triad, though this combination appears in only half of ruptured AAA cases. 4, 3
• The classic presentation includes acute back pain with a pulsatile abdominal mass, often associated with retroperitoneal hemorrhage. 4, 1

Pain Characteristics

• Acute abdominal pain, back pain, or flank pain indicates impending rupture and necessitates immediate emergency evaluation. 1
• Pain may be described as "sharp" or "stabbing" rather than the classic "tearing" or "ripping" quality seen in aortic dissection. 1
• Back pain is present in 65-90% of symptomatic cases and occurs less commonly in uninfected atherosclerotic aneurysms. 4
• Pain can radiate into the lower back, groin, or lower extremities. 5
• Lower back pain alone may be the only symptom in chronic contained rupture, potentially mimicking lumbar radiculopathy for months. 6

Associated Symptoms with Rupture

• Hypovolemic shock may occur with frank rupture, presenting with hypotension and signs of poor perfusion. 1
• Fever is present in ≥70% of patients with mycotic aneurysms but is uncommon in uninfected atherosclerotic AAAs. 4
• Absence of distal pulses may occur, though AAAs typically maintain blood flow to lower extremities until rupture. 5

Rare Symptomatic Presentations

Compression-Related Symptoms

• Neurologic lower limb motor or sensory deficits can occur from compression of neural structures, particularly with vertebral body erosion. 4
• Vertebral body erosion from chronic contained rupture may cause isolated spinal cord or radicular nerve compression symptoms without systemic signs of rupture. 4

Atypical Presentations

• Symptoms may be so atypical that AAA rupture can mimic other acute abdominal conditions, including acute cholecystitis, leading to fatal diagnostic delays. 7
• The condition is easily misdiagnosed because symptoms related to aortic disease may be subtle. 4

Physical Examination Findings

• A pulsatile abdominal mass above the umbilicus may be palpable, though obesity makes detection difficult. 5
• The abdominal aorta splits at the level of the umbilicus, so palpation must occur above this level to detect aortic enlargement. 5
• Capillary refill and temperature remain normal until rupture occurs, as blood flow to extremities is maintained. 5

Critical Clinical Pitfall

The absence of the classic triad does not exclude AAA rupture. Only 50% of patients with ruptured AAA present with all three classic findings, and many present with isolated back pain or atypical symptoms that can be mistaken for musculoskeletal conditions, cholecystitis, or other non-vascular emergencies. 4, 3, 7 Maintaining high clinical suspicion in at-risk patients (men >65 years, smokers, hypertensive patients) with any combination of abdominal or back pain is essential. 4, 8