A 79-year-old female presented to the ED via EMS after a fall. She slipped in the living room and hit her head on a coffee table. There was no loss of consciousness. She did have an episode of emesis after the event. She was found on the floor hours later, unable to get up. She did take aspirin occasionally, but was not taking any other blood thinners.


Initial VS: BP 154/76, HR 98, SpO2 98% on RA


Physical exam revealed an elderly female who was alert and oriented to person, place and time. She had a hematoma and 4 cm laceration over her right eyebrow.


A FAST exam was performed to look for other signs of traumatic injures. When the transducer was placed in the lower abdomen this was seen:

Is this this the bladder?


The clinicians taking care of the patient thought not and decided to put color Doppler over the anechoic structure. See below:

This in an abdominal aortic aneurysm (AAA).


In the abdomen, if the aorta is greater than 3 cm in diameter, it is considered to be an aneurysm. When imaging to rule out an aneurysm we like to look at the proximal, mid, and distal aorta near the bifurcation because aneurysms can be found in any of these locations. If you find an aneurysm that looks like this, we would also recommend doing a FAST exam to look for free fluid, especially if you are worried about rupture.

This patient had a complete FAST exam done, which was otherwise negative. This, however, did not rule out  rupture because some aneurysms will rupture into the retroperitoneum and will not be appreciated on FAST exam.

Even though there may be an aneurysm present, it does not mean that the patient needs an operation. Most surgeons do not operate on asymptomatic AAAs unless they are greater than 5.5 cm because the risk associated with surgery is greater than that of rupture of the aorta.


This patient had a HCT in the ED, which was negative for intracranial hemorrhage. She also had CT imaging of her aorta, which revealed a non-ruptured 8 cm infrarenal aneurysm.

Vascular surgery ultimately recommended elective endovascular repair. Her fall was felt to be unrelated to the aneurysm.


Bottom Line:

  1. A normal abdominal aorta is generally considered to be <3 cm.
  2. In asymptomatic aneurysms, repair is generally not considered until the aneurysm is >5.5 cm.


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