I`ve had 4 BCG sessions and this will be the third cystosopy since surgery , I do get lower back pain and also some lower flank twinges but I`ve had these on and off for decades , other than the cancer I`m pretty fit , not over weight , dont smoke , eat healthy and walk over 35 miles a week .I had bladder cancer around 9 years ago and now I don't.
Surgery was done trans-urethra with fibre optic instruments. All is well.
I go to see the surgeon every 4-6 months and he does a cystoscope exam which I expect is what you will have
Each time no cancer seen.
For those wondering or worried, a cystoscope in a modern hospital puts a flexible instrument with camera and light (and lumen for fluid) up into the bladder and he looks around. The cystoscope is in medical sizes "sixteen French" which seems to be about 5mm. Before the procedure the nurse cleans the head of the penis and squirts Lidocaine gel into the urethra to numb things. It is an odd feeling but not painful with a feeling of pressure as they pass the prostate (at least for me). When they look around inside they put saline solution into the bladder so they can see every nook and cranny. They drain it out but after the tube comes out you might piss yourself. That is a small price to pay for knowing you are cancer free.
If the doctor has not called to reschedule it he must feel it is important. If he calls to reschedule he must think things are likely to be OK.
If this is the first cystoscope exam after surgery I am a bit surprised. Here in the US the first cysto is usually at 3 months, then 4-6 month intervals after that.
Good luck for the exam and also for your wife's illness.