Hematuria is the presence of red blood cells in the urine. Visible hematuria, also known as gross hematuria, is easily identified, as it causes red or brown discoloration of the urine. Microscopic hematuria is invisible to the naked eye and is often found incidentally on urinalysis or urine dipstick. Any part of the kidneys or urinary tract (ureters, urinary bladder, prostate, and urethra) can leak blood into the urine. The causes of hematuria are broad, ranging from urinary tract infection to kidney stones to bladder cancer.