An endoleak is a problem that can happen after a procedure called endovascular aneurysm repair (EVAR). In this procedure, a device called a stent-graft is placed in the blood vessel to strengthen it and prevent the aneurysm from bursting.

An endoleak occurs when blood leaks around the stent graft but stays inside the aneurysm. This means the stent isn’t fully stopping blood flow into the weakened area, which could cause the aneurysm to grow or put pressure on the stent.

There are different types of endoleaks, depending on where and how the blood is leaking.