Fusiform aneurysms are the type most commonly seen in the abdominal aorta. Most fusiform aneurysms are true aneurysms. The weakness is often along an extended section of the aorta and involves the aorta's entire circumference. The weakened portion appears as a roughly symmetrical bulge, as shown in the image bottom left.
Saccular aneurysms appear like a small blister or bleb on the side of the aorta and are asymmetrical, as shown in the image. They may be pseudoaneurysms caused by trauma, such as a car accident, or by a penetrating aortic ulcer (image bottom middle).
Dissecting aneurysms occur when a tear begins within the wall of the aorta causing the wall layers to separate, as shown in this CT image. Dissections can cause aneurysms, but an existing aneurysm can also dissect. This is more commonly seen in the thoracic aorta (image bottom right).
Fusiform aneurysm | Saccular aneurysm | Dissecting aneurysm |
Click the image to see a larger version | Click the image to see a larger version | |