A lot of people with PSC don't have any symptoms, I think it is most often caught from irregular bloodwork and then further tests. The only symptoms that the heptologist asked me if I had were itching or upper right quadrant pain where your liver is. I never had any symptoms, it was my bloodwork that caused my Dr to send me for an MRI and they made the diagnosis from that.
From what I know there is really no way to prevent it most people who have it have had UC awhile. I think I read 75% of PSC patients have UC or Crohn's but it is most common in UC.
There really isn't a treatment so for now I have just been watching my diet, no alcohol/no gluten, low sugar and trying to keep my toxic load to a minimum so my liver doesn't get over worked.