When I was younger the doctor completely cut off my bladder stem, I had to have one make the doctors told me that it was made out of pig skin and would only last about 10 years. The surg and post op was very painful and it has lasted for 26 years. About 5 years ago I had hyst. the doctors said that it was very thin and did I want them to replace it. I told them NO. How will I know when there is no choice that I have to have it replaced.