Vesicoureteral reflux (VUR) is the backward flow of urine. The urine flows from the bladder back into the kidney.

Urine normally flows from the kidneys. It passes through tubes called ureters. It then flows into the bladder. Each ureter connects to the bladder in a way that prevents urine from flowing back up the ureter. The connection is similar to a one-way valve. When this does not work properly, or if the ureters do not extend far enough into the bladder, urine may flow back up to the kidney. If the urine contains bacteria, the kidney may become infected. The back up can also put extra pressure on the kidney. This can cause kidney damage.

Anatomy of the Urinary System
The Urinary Tract
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This condition may be caused by:

  • A problem in the way the ureter inserts into the bladder
  • A ureter that does not extend far enough into the bladder
  • A bladder outlet obstruction, such as a blockage of urine flow from an enlarged prostate gland
  • A neurogenic bladder—loss of normal bladder function due to damaged nerves reaching the bladder
  • Temporary swelling after a kidney transplant