Evaluation. Any portion of the urinary output tract can bleed. This can be due to trauma, infection, vascular tumors, malignancies or stones. Unless you are in pain or cannot easily urinate, you can make a quick appointment with your urologist. If the symptoms are severe or the urine is full of blood, go to an er.
See your doctor. Blood is normally not found in urine. Are there symptoms like burning with urine, flank pain, recent infection, etc? Injury or recent surgery could also cause this. In females this is common with recent period. See your doctor for further follow up as this needs to be looked at in a clinical context to be sure everything is good.
Various things. This needs attention could be kidney stones or problems along your urinary tract from kidney to bladder to even testicles. I suggest seeing your doctor for repeat urinalysis imaging and work up.
Get evaluated. You should definitely seek a medical opinion if you have seen blood in your urine. This could indicate infection, stone, or tumor in the renal system (kidney, ureter, and bladder.) please, , contact your doctor and express your concerns.
Red blood cells. This is the same as red blood cells in urine. This should be confirmed by a microscopic look at the urine. Could be coming from anywhere from the kidney ureters or bladder.