How and where to palpate an Abdominal Aortic Aneurism?

Abdominal Aortic Aneurysm is a focal ballooning of the infradiaphragmal aorta, traditionally defined as a diameter greater than 3 to 4 cm. It is a disorder of elderly patients, affecting 1% to 2% of patients over the age of 50.

Abdominal Aortic Aneurysms tend to enlarge slowly, but some rupture catastrophically with an overall mortality of up to 90%.

How to find it:
Because the normal aorta bifurcates at the level of the umbilicus, palpable aortic aneurysms usually are found in the epigastrium or left upper quadrant.

The osteopath places one hand on each side of the aorta and measures its diameter, subtracting the estimated thickness of two layers of skin and subcutaneous tissue. This palpation is of course not really reliable; ultrasound examination is much more objective.

When an aortic aneurysm pushes the two hands apart, this is a finding called expansile pulsation.

The finding of a palpable epigastric pulsation suggestive of aneurysm increases the probability that one is present. The absence of this finding is much less helpful, simply because the sensitivity for the finding is as low as 22% (up to 78% of patients with aneurysms lack a prominent pulsation).

The two most important variables governing whether an aneurysm is palpable are:
• The size of the aneurysm.
• The girth of the patient’s abdomen.

Aneurysms between 3 and 5 cm in diameter are difficult to detect manually, and if aneurysm is instead defined as a focal bulging of more than 5 cm in diameter (this usually indicates surgical repair) the sensitivity of manual examination increases to more than 80%.

Aneurysms are also more difficult to detect in patients with larger abdominal girths.

When the patient has a girth of less than 100 cm and the aneurism is 5 cm or more the palpability is 88%.