Aside from infection, venous stenosis is another serious problem with catheter access. The catheter is a foreign body in the vein and often provokes an inflammatory reaction in the vein wall. This results in scarring and narrowing of the vein, often to the point of occlusion. This can cause problems with severe venous congestion in the area drained by the vein and may also render the vein, and the veins drained by it, useless for creating a fistula or graft at a later date. Patients on long-term hemodialysis can literally 'run out' of access, so this can be a fatal problem.