A wound in the bladder?!

Patient: Dear DoctorMy father had a successful prostate operation and after almost four years he took a CT scan requested by his heart doctor and everything was fineTwo weeks after the scan he saw a blood come out with the urine and also not just a blood but a small pieces of bloodWith no painThese symptoms the flow of blood in the urine lasted for a day and a half later came back normal urine for a dayAfter that we went to the emergency department and the doctor took a blood test and said everything is fine and said do not worry if the blood come againUnfortunately it comes again just one day after we went to the emergency departmentAnd my father is in a great concern and can not sleep because it is holiday now and his next appointment is not soonHis major questions arewhy this is happeningwhat are the reasonsWhat is the cause of the flow of bloodThe patient felt great concernDoes this mean that his prostate operation was not successfulIs this situation dangerousWhile we are waiting for his appointment what can we do nowHow we can came down my fatherAny help is appreciatedThank youHA