If a patient is found to have hematuria, but it has only occurred once, it may not be caused by hematuria, such as the recent intake of reddish colored foods, such as red heart dragon fruit and beet stalks, which can cause red urine. Therefore, after a transient reddening of the urine, the color will not continue to worsen. There are also transient hematuria of the urinary system, such as having stones that damage the mucous membrane of the genitourinary tract in the process of discharge, and the blood that exudes from the scratched local mucous membrane will heal itself within a day, so it will only occur once. Some patients have lesions in the mucosa of the bladder or ureter, such as localized tumors or malformed vascular masses in the mucosa, and in this case, bleeding will occur once in a while, but after a while, it will stop due to the self-repair of the mucosa. Therefore, when this problem occurs, patients are advised to undergo timely examination to clarify the specific cause of the bleeding.