My son has a thrombosis in his supra-mesenteric artery after surgery to remove his colon last July. He is awaiting further surgery to form a pouch and has been told he will have to come off the warfarin first. Will this have to be gradual withdrawal? Also the consultant said he will probably have this thrombosis for the rest of his life. When I asked if it might move towards his heart he said " no it will not move" how does he know that? The new surgery he said is very risky. " Life threatening " I asked. " well crossing the road is life threatening" what kind of answer is that? Why can't you get straight answers? I'm now extremely worried.