Aneurysm Types

There are two major groups of aneurism: a true aneurysm and a false aneurysm. In a true aneurysm, all three layers of a blood vessel (the intima, the media, and the adventitia) bulge outwards, but the swelling is contained by the outer wall and the blood remains within the confines of the circulatory system. This group of aneurism may be due to congenital malformations, infections or hypertension. A false aneurysm (also known as a pseudo-aneurysm or pulsating haematoma) is a contained rupture through all three layers, where the blood leaks from the artery into the surrounding tissue.

Aneurysms may also be described according to their shape: saccular or fusiform. A saccular aneurysm resembles a small, rounded sack, and involves only a portion of the vessel wall. They are usually between 5 and 20 cm in diameter, and are often partially or totally filled with blood clot. A fusiform aneurysm is shaped like a spindle, and is a gradual progressive dilation of the complete circumference of the vessel. This type of aneurysm can measure up to 20 cm in length, and usually occur in the aorta or the iliac arteries.