**2. Definition**

All aneurysms can be classified by location, size, shape and etiology. However, there is always significant confusion about what a false aneurysm or pseudoaneurysm is. True aneurysm presents with all three layers of arterial wall. Pseudoaneurysm or false aneurysm occurs as result of blood flow outside the normal layers of the arterial wall. Basically blood is going through the hole in the wall of artery into contained space outside. That blood is compressed by surrounding tissue so it finally reenters the artery during the cardiac cycle. Repeating this process, false aneurysm (outside the artery) begins to grow.

False aneurysm could be caused by trauma, infections, iatrogenic or every kind of conditions that could promote focal weakness within the arterial wall.
