Don't worry if they say you need a cystopscopy ( camera in the bladder). I have had a lifetime of occult blood in urine and was investigated for it when I was 19 ( I am now 54) with an iv x ray of kidneys and bladder but when I moved and changed Dr surgery the new one asked if I would have the cystoscopy to rule out being born with tiny polyps in bladder as was only thing left to test for
I had it done and it was no problem, they use local anaethetic gel in your urethra and the test itself was not even uncomfortable. Once the gel wears off then you feel a bit as if you have UTI for a few hours but if you drink plenty it passes quickly and I was totally fine next morning.
The cause of my lifelong hidden blood in urine is big filters on my kidneys so blood and things can pass through.