Usually urine reflux is caused by impaired function of the ureteral orifice or excessive pressure in the bladder. Under normal circumstances, urine produced by the kidneys enters the bladder through the ureter for storage, and the ureteral orifice prevents urine from refluxing into the kidneys. When the congenital ureteral orifice site develops abnormally or the barrier mechanism of the ureteral orifice is impaired after a surgery, this can lead to the fact that urine can retrograde into the ureter and kidneys, causing reflux. In addition, obstructive diseases of the lower urinary tract can lead to excessive pressure in the bladder, such as prostatic hyperplasia and urethral stones, so that urine can retrograde reflux into the kidneys, causing hydronephrosis and affecting renal function. Whichever cause of urinary reflux needs to go to the hospital in time.