An aneurysm is an abnormal dilatation of a blood vessel. Aneurysms cause problems either by bursting causing major bleeding, or by blocking, starving the organs downstream of their blood supply. The two commonest sites for aneurysms are the infrarenal aorta (at the back of the abdomen just below the kidneys) and the popliteal artery which is behind the knee. Aneurysms can however occur in almost any artery in the body.
Some types of aneurysms are much more common than others. The most frequently seen kinds are described in detail in their sections of the website (please see Conditions Treated, Prevented and Cured). Aneurysms also occur in the brain, and may cause brain haemorrhages and strokes. These aneurysms are not related to peripheral aneurysms, and are usually treated by neurosurgeons and neuroradiologists.