I suffered several incidents of blood clots and blood loss in my urine but only after about 16 months after RT had finished. It was quite disturbing when it first happened as it seemed as if I was peeing pure blood for a while. I even when to the emergency late night doctor service that our local hospital has, taking with me an empty jam jar of the urine/blood.
Things did return to normal in the days that followed and a cystoscopy found that my bladder was ok. I did have a further incident about a month later but since then things have been ok.
The conclusion was that, in some way, the bleeding was caused by the late effects of having the RT.