6. Injury to the bladder
Though it may seem unlikely, the bladder can actually sustain injuries. These injuries can be the result of a car or a sporting accident, for example. Since the bladder houses urine until it is passed, it makes sense that blood could appear. This happens when the injury causes blood cells to pass into the urine, and injuries are associated with the release of blood cells.
Other symptoms are typically associated with a bladder injury, aside from blood in the urine. These symptoms can include pain while urinating, or pain and tenderness when pressure is placed on the urine.