My husband had the same thing happen to him: neobladder surgery, blocked ureters, then nephrostomy tubes draining the kidneys directly into external bags. Then a second neobladder surgery, but the same thing happened. We were told that chemo increases the risk of scar tissue. After each surgery the stents remained for a couple of months, were removed and then blockage.
He did not survive all of this, but in hindsight, we both wished he had just opted for the ostomy bag in the first place.
I wish you good decisions and healing...
Judy