What leads to blood in urine?

Patient: I am a 16 year old girl and I have recently discovered blood in my urine. I would like to know why this is happening and should I be worried about it?

Doctor: Blood in the urine could be due to a urinary tract infection , a renal stone, trauma, due to medications or vaginal blee ding which is mixing with the urine and manifesting as blood in urine. This is a concerning symptom which needs attention and thus needs to be evaluated further as to the cause. Please consult your family physician for further testing like a urine analysis.