The visible sign of hematuria is pink, red or cola-colored urine — the result of the presence of red blood cells. It takes very little blood to produce red urine, and the bleeding usually isn’t painful. If you’re also passing blood clots in your urine, that can be painful. A lot of times, though, bloody urine occurs without other signs or symptoms.

In many cases, you can have blood in your urine that’s visible only under a microscope (microscopic hematuria).