Prolonged holding of urine can lead to hematuria, this is because a long period of holding a large amount of urine bladder in a state of filling, prolonged filling or overfilling can lead to small blood vessels on the surface of the bladder oozing blood, which can be manifested as hematuria. Can also be seen in the sudden emptying of the bladder of urine, the bladder pressure suddenly drop, in the low-pressure state of the small blood vessels can also be due to the gradual decline in pressure in the bladder, resulting in a sudden increase in the hydrostatic pressure of the blood vessels, there will be a small blood vessel rupture and bleeding, commonly found in a variety of patients with urinary retention to give the catheterization of the indwelling urinary pressure decreases caused by the release of the urine too quickly, which appeared to be the urinary tract of the bleeding, bleeding can even be caused by the bladder of the serious cases Hematoma or the formation of large blood clots. In daily life need to avoid holding urine for a long time, if because of disease conditions lead to excessive holding urine, need to give indwelling catheterization, indwelling catheterization process need to intermittent release of urine, release of urine 300-400mL or so need to be placed again at intervals of 1 hour, until the bladder is completely empty until the bladder in order to prevent the occurrence of bleeding phenomenon.