My 12 year old son has occasionally had blood in his urine. Not much, and probably wouldn't have notices if he hadn't "dribbled" a bit on the side of the toilet bowl, as it wasn't enough to color the water, just the drops. This happened 3 times during the last week. We took him to the doctor and they sent him for tests today (ultrasound of kidneys and bladder) as well a full blood work-up. We will get results in a few days. Tonight when he went to the bathroom, there were actual drops of blood that came out after he urinated. They were much heavier, obviously, and dropped to the bottom of the bowl. Should we wait until tomorrow to follow-up with his doctor, or head to the ER?