Vesicoureteral reflux (VUR) is the name of a condition in which there is abnormal flow of urine backwards from the bladder into the ureters. It is mostly seen in the pediatric population and may manifest as either a primary or secondary condition.
Primary VUR occurs in the presence of an otherwise normally functioning lower urinary system, whereas secondary VUR arises due to obstruction or dysfunction within the lower urinary system.
Primary VUR is congenital, so that its cause occurs before the birth of the affected baby. While the exact cause of primary VUR is yet to be determined, it is believed to have a genetic component. Some authorities believe that secondary VUR is linked to recurrent UTIs, but others suggest that the two phenomena are independent of each other. Despite variations in etiology, both cases manifest as a failure of the valvular mechanism at the ureterovesical junction (UVJ), which normally blocks urine from flowing backwards into the ureters from the bladder.
Primary VUR may present before the child is born as hydronephrosis in utero. This condition refers to the swelling of the kidneys due to the accumulation of urine within the renal collecting system. It is visualized with the help of an obstetric ultrasound. After birth, infants and children with VUR may present with several nonspecific signs and symptoms that vary depending on age. Most notably, these children tend to have recurrent urinary tract infections (UTIs).
Infants may exhibit a failure to thrive as well as lethargy, diarrhea, vomiting and anorexia. These signs and symptoms may or may not be accompanied by fever. Moreover, affected infants may be more irritable than usual and do not respond to calming techniques that are normally successful.
In older children, parents may report fever and abdominal pain and/or discomfort. If the UTI develops into the more serious condition called pyelonephritis which refers to infection within the kidney parenchyma, the child may have vague discomfort in the abdominal area as opposed to the classical pain in the flank seen in adults. Children may pass frequent small quantities of urine which has a strong odor, with micturition being accompanied by a burning sensation. Furthermore, the urine may be cloudy or there may be blood in it.
Children with VUR may appear healthy for the most part. In fact, VUR typically may not cause any symptoms if it is not associated with any complications. The first suspicion, most often, occurs only after the child develops a UTI with fever and other accompanying signs and symptoms. However, those who have hydronephrosis in utero diagnosed on the basis of an ultrasound are likely to have their VUR picked up very early in their infancy.
Untreated, VUR can cause serious complications. Kidney pathology due to the reflux of urine is one of the leading causes of hypertension in childhood. The degree of kidney scarring is proportional to the severity of the hypertension. Furthermore damage to the kidneys impairs their ability to filter and concentrate urine. The most devastating consequence of VUR is kidney failure. Fortunately, it is believed that this dire outcome only occurs in a very small percentage of children affected by VUR.
Reviewed by Liji Thomas, MD.