Blood in urine

The doctor found traces of blood in my urine culture, and my period was 2 weeks ago. I have been noticing some slightly "old blood" traces now and then, but thought it was from the menopause.  He says no, and is sure its from the urine. I am thinking that its from the vagina. I have no UTI so thats ruled out. He diagnosed it as Hematuria (sp error?) How can they tell if its actually from the urine, or if its coming from the vagina?  Anyone have this problem?