I've had my fistula for about 5 years now. It hasn't gotten worse. And my surgeon says that it could just stay like this forever, as long as it is not causing me problems.It has really stayed very consistent over the last 5 years. The first year was the only time I noticed up and downs. I can only presume that it is similar to a hole in your ear for an earring. After a while the hole is there to stay and the inner lining is all healed up.
I never have actual stool leaking from my vagina either.I guess my fistula tract is very small, or is in an optimal location. I do have air pass through my vagina. Only when I am lying down though. As weird as this may sound, I like having this "air valve", since most j-pouchers can't pass gas whenever they like.