Abdominal aortic aneurysm rupture

Abdominal aortic aneurysm (AAA) rupture is a feared complication of abdominal aortic aneurysm and is a surgical emergency. It is part of the acute aortic syndrome spectrum.

Abdominal aortic aneurysms are common and affect ~7.5% of patients aged over 65 years 6.

The classical triad of pain, hypotension and pulsatile abdominal mass due to rupture into the retroperitoneum is only seen in 25-50% of patients. 

A chronic rupture may escape detection for about weeks to months and are known as sealed aneurysmal rupture or spontaneously healed aneurysmal rupture or abdominal aortic aneurysmal leak. 

Unusual presentations of ruptured abdominal aortic aneurysm are

  • transient lower limb paralysis
  • right upper quadrant pain
  • groin pain
  • testicular pain
  • testicular ecchymosis (blue scrotum sign of Bryant)
  • iliofemoral venous thrombosis

The aneurysmal rupture is thought to occur when the mechanical stress is in excess of the wall strength. Thus, the aortic aneurysmal wall tension and the aneurysmal diameter are a significant predictor of impending rupture. 

The commonest sites of rupture and their relative incidences are

Plain radiograph

Abdominal radiographs are not a sensitive mode of detection. A calcified aortic aneurysm may be seen with a secondary blurring of the psoas outline in case of retroperitoneal haemorrhage.

Ultrasound
  • focal dilatation of the aorta (aneurysm)
  • peri-aortic fluid
  • free intraperitoneal fluid
  • retroperitoneal fluid: representing retroperitoneal haemorrhage
CT / CT angiography

Retroperitoneal haemorrhage adjacent the aneurysm is the most common finding. The peri-aortic blood may be seen to extend into perirenal or pararenal spaces, or the psoas muscles. Intraperitoneal extension of the haemorrhage may be seen as an immediate or a delayed finding. 

An important feature seen in contained rupture of an aortic aneurysm is the draped aorta sign - in which the posterior wall of the aorta is not seen distinctly from adjacent structures, and the contour of the aorta follows that of adjacent vertebrae. 

A hyperattenuating crescent sign, which is an area of increased attenuation within the aortic aneurysmal mural thrombus, can be demonstrated on plain CT images. This is caused by the insinuation of fresh blood into the mural thrombus and aortic wall.

On post-contrast studies or CT angiography, active extravasation of contrast material can be seen.

Findings predictive of impending rupture
  • increased aneurysm size on serial imaging (rate of 10 mm or more per year)
  • very large abdominal aortic aneurysm > 7 cm
  • reduced thrombus size
  • thrombus fissuration
  • discontinuity in calcification
  • hyperattenuating crescent sign
  • well defined peripheral crescent of increased attenuation within the thrombus of a large abdominal aortic aneurysm

Treatment of an acute rupture should be prompt and can be with endovascular aneurysm repair (EVAR) or open surgery. The mortality rate is very high being > 90% 6

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Article information

rID: 25600
System: Vascular
Synonyms or Alternate Spellings:
  • Aortic aneurysmal rupture
  • Abdominal aortic aneurysm rupture
  • Ruptured abdominal aortic aneurysm
  • Rupture of abdominal aortic aneurysm
  • Abdominal aortic aneurysmal rupture
  • AAA rupture
  • Rupture of AAA
  • Rupture of an AAA
  • Rupture of an abdominal aortic aneurysm

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