Blood in the urine. It usually indicates injury or disease of the kidney or another structure of the urinary system or possibly, in males, the reproductive system. It may result from infection, inflammation, tumours, kidney stones, or other disorders. How the blood looks and when it appears in the urine stream reflect whether it originates in the urethra, the bladder, or the kidney
blood in the urine; gross hematuria is sufficient blood in the urine to be visible, microhematuria is a minute amount of blood in the urine small enough to require microscopy or other methods of detection