You should get a scan done of the prostate and testicles etc. an ultrasound might be enough.
Hmmm… I wouldn’t be too worried about occasional blood in Semen, but if it’s been ongoing for a year or more, that would definitely concern me. Now here’s another question: Has this just been occurring occasionally for a year or more, or is it every single time? I’d be especially worried if it were every time. If this were me, I’d probably go see another Urologist & get a 2nd opinion. If you do, let us know what you’re told about it.