Mel, nephrostomy tubes are used when the ureter is blocked to drain the kidney. My husband's ureter was partially blocked by his CIS so they put a stent in his ureter to keep the kidney draining. In this case they keep a stent in place and change it about every 3 months. They need to do one or the other to keep the kidney working. They tell me it is very painful if the kidney can't drain and starts to swell.
As for hope I think there is always hope but what you hope for may change over time.
There has definitely been a setback. The MRI showed that there are tumors growing back in the bladder (my father still has his bladder because there were mets to the bone) and going up the ureters. I guess this is what is causing the blockage. I am in complete shock because a month ago we had a PET scan that showed there were no tumors in the bladder and things were looking good. Now, I feel like there is no hope again.