In my 40s. recurring rbc in urine for years. urologist recommended cystoscopy. is it really necessary at this point since it's been yrs? if it cancer, wouldn't i have known it by now? can interstitial cystitis cause this? would prefer to avoid test?

Risk/Benefit equaton: Hematuria, is a term used to describe blood in the Urine; it can be visible to the eye(then called Gross) or invisible to the naked eye(then called microscopic hematuria). It seems, you have microscopic hematuria which can, sometimes be benign but we need to know the duration(number of years) and number of red blood cells(RBC) in your urine tests. Then we can guide you further.

Microhematuria: Interstitial cystitis can cause bleeding, gross or microscopic,in the urine. Noninvasive methods to check for bladder cancer are ultrasounds, cytology analysis for malignant cells, FISH analysis,and MRI of the bladder. Your urologist can advise you best, however.