What Causes Traces Of Blood In Urine After A Total Hysterectomy?

Hello. I am 60 hrs old had a complete hysterectomy 25 hrs ago. I have been experiencing back ache almost daily,bloating and passing blood clots but not upon urinatioon. Test revealed a trace amount if blood in urine. No temps or infections in urinary trac , ultra sound of the pelvis and vaginal area are very normal . Where could this blood be coming from if I have no uti or vaginal prob.