Reflux nephropathy is a condition in which the kidneys are damaged by the backward flow of urine into the kidney.
Causes, incidence, and risk factors:
Urine flows from the kidneys, through the ureters, and into the bladder. Each ureter has a one-way valve where it enters the bladder, preventing urine from flowing back up the ureter.
Reflux nephropathy occurs when these valves fail, allowing urine to flow back up to the kidney. If the bladder is infected or the urine contains bacteria, the kidney become infected (pyelonephritis ).
Because the pressure in the bladder is generally higher than in the kidney, the reflux of urine exposes the kidney to unusually high pressure. Over time, this increased pressure will damage the kidney and cause scarring.
Reflux can occur in people whose ureters do not extend very far into the bladder. The ureters enter the bladder through "tunnels" in the bladder wall, and the pressure in the bladder normally keeps these tunnels pressed closed. If the bladder-wall tunnels are short or absent, pressure within the bladder can force urine back up the ureter.
Reflux can occur with other conditions, including the following:
Reflux nephropathy is often found when a child is checked for repeat or suspicious bladder infections. If reflux is discovered, the child's siblings may also be checked, because reflux can run in families.
The degree of reflux -- separated into five different grades -- helps determine treatment. Simple reflux often falls into grade I or II.
Reflux nephropathy also can occur from temporary swelling after the ureters are reimplanted during a kidney transplant or because of trauma to the ureter.
The risk factors include a personal or family history of reflux, abnormalities of the urinary tract, and repeat urinary tract infections.
Some people can have no symptoms from reflux nephropathy. There may be no symptoms if only one kidney is affected. If symptoms do occur, they might be similar to those of a urinary tract infection , nephrotic syndrome , or chronic kidney failure .
Other symptoms that can occur with this disease include the following:
Note: The disorder may not cause symptoms.
Simple, uncomplicated reflux (called primary reflux) less than grade III can be treated by the following:
- Careful watching
- Repeated urine cultures
- Yearly ultrasound of the kidneys
More severe reflux may require surgery, such as the following:
- Ureteral reimplantation
- Reconstructive repair
Surgery to place the ureter(s) back into the bladder can be done to stop reflux nephropathy. This surgery results in less frequent and less severe urinary tract infections.
The outcome varies. Most cases of reflux nephropathy get better on their own. However, the damage to the kidney may be permanent. If only one kidney is involved, the other kidney may continue to function.
Reflux nephropathy may cause kidney failure in children and young adults.