What is (are) Vesicoureteral Reflux ?
The two types of VUR are primary and secondary. Most cases of VUR are primary and typically affect only one ureter and kidney. With primary VUR, a child is born with a ureter that did not grow long enough during the childs development in the womb. The valve formed by the ureter pressing against the bladder wall does not close properly, so urine refluxes from the bladder to the ureter and eventually to the kidney. This type of VUR can get better or disappear as a child gets older. As a child grows, the ureter gets longer and function of the valve improves.
                
Secondary VUR occurs when a blockage in the urinary tract causes an increase in pressure and pushes urine back up into the ureters. Children with secondary VUR often have bilateral reflux. VUR caused by a physical defect typically results from an abnormal fold of tissue in the urethra that keeps urine from flowing freely out of the bladder.
                
VUR is usually classified as grade I through V, with grade I being the least severe and grade V being the most severe.