Vesicoureteral reflux (VUR) is a condition in which urine backwashes back up in the ureters/kidneys from the bladder. Urine will typically flow from the kidneys, drain down the ureters and then get stored in the bladder. The urinary tract is your body’s drainage system for removing waste and extra water.
https://my.clevelandclinic.org/health/diseases/5995-vesicoureteral-reflux

