Fistulas can get large. Aneurysms can get large (mine did) but that is just aesthetics, unless they become symptomatic (ditto). The symptoms are silvery thin skin, and pain. Since mine was removed, I have been amazed at how pain free I am. My fistula was a garden hose, and I would have kept it forever. (garden hose is good - not pretty, but good).
How your fistula looks really is based on your own physiology (how you body is), your surgeon, and the placement. I had a Left up arm fistula that we knew would grow as the years go by, because I am a big woman (5'10"), why should my veins be small when my arms are 36" long? I also have PKD which has a co-morbidity of aneurysms, and I was at a BAD incenter clinic for 10 months before I was able to cannulate myself. All in all, a BAD combination.
An aneurysm is a weakness in the wall of a blood vessel, in the case of a fistula, in the vein that has been artificially manipulated to act as an artery close to the skin so that we can have high volume blood access for dialysis. Bad cannulation, could cause them as could just dumb luck.
Stenosis is the true enemy of fistulas as it has been said above. Aneurysms just need to be watched.
I posted about the history of my fistula (along with photos of the beginning and end of my aneurysm), but I think that maybe we should have a fistula photo gallery. They do come in all shapes and sizes. EpoMan was worried that people would be scared by seeing some of the more twisted ones, but I am thinking that if we see the variety of what is out there, maybe we will become de sensitized...
Here is a link to my Fistula Post (with pictures)
http://ihatedialysis.com/forum/index.php?topic=18735.0There you go Richard.. I've shown you mine, now you show me yours!!