Vesicoureteric reflux (VUR) describes the flow of urine from the bladder into the upper urinary tract when the ureterovesical junction fails to perform as a one-way valve. Most commonly, VUR is primary, though it can be secondary to bladder outflow obstruction and can occur in several multiorgan congenital disorders. There is good evidence of a genetic basis with a greatly increased risk of VUR in children with a family history of VUR. VUR is a congenital disorder, which largely shows improvement or complete resolution with age. Fetal VUR may be associated with parenchymal developmental defects (dysplasia). Postnatally non-infected, non-obstructed VUR does not appear to have a detrimental effect on the kidneys. However there is an association of VUR with urinary tract infection and acquired renal parenchymal defects (scarring). The parenchymal abnormalities detected on imaging, often termed reflux nephropathy, may be as a result of reflux-associated dysplasia or acquired renal scarring or both. It is difficult to distinguish between the two on routine imaging. Higher grades of VUR are associated with more severe reflux nephropathy. The precise role of VUR in pyelonephritis and scarring is not clear and it may be that VUR simply increases the risk of acute pyelonephritis. Whilst most VUR resolves during childhood, it is associated with an increased risk of urinary tract infection and burden of acute disease. Investigation strategies vary considerably, related to uncertainties about the natural history of the condition and the effectiveness of various interventions. The long-term prognosis is chiefly related to the morbidity of reflux nephropathy leading in some cases to impairment of glomerular filtration rate, hypertension, proteinuria, and pregnancy-related conditions including hypertension, pre-eclampsia, and recurrent urinary tract infection. Management is controversial and ranges from simple observation with or without provision of rapid access to diagnosis and treatment of urinary tract infections; to long-term prophylactic antibiotics or various antireflux surgical procedures.
Pathogenesis of gestational urinary tract infection: urinary obstruction versus immune adaptation and microbial virulence
