Blood in your urine can be a startling sight, one that prompts concern over your health. While it doesn’t always mean something serious, several serious things can cause it. And that means you should contact your doctor right away.

It’s also important to understand what’s going on in your body. You may see a range of colors — from pink or slightly dark urine to bright red or cola-colored liquid. You may also see clots, which can come from your prostate, urethra, kidneys or ureters (tubes connecting your kidney to your bladder).