Vesicoureteral reflux (VUR) is the backup of urine from the organ that stores urine (bladder) into the tube that carries urine from the kidney to the bladder (ureter) during urination. VUR may result in urine reflux into the renal pelvis, causing distention (hydronephrosis) and kidney damage. In children, this condition is usually caused by an abnormality that is present at birth (congenital) and is often diagnosed during prenatal ultrasound.
What is the normal urinary tract?
The urinary tract consists of the kidneys, ureters, bladder and urethra. The kidneys are the organs that are responsible for filtering waste products from the bloodstream and produce urine continuously. The urine drains down tubes called ureters from the kidneys to the bladder, which normally stores urine and empties intermittently by muscular contraction. The urine exits the bladder through the urethra in a process is called voiding or urination.
When the ureter enters the bladder it travels through the wall for a distance creating a tunnel so that a flap valve is created. This valve prevents urine that is in the bladder from backing up and returning into the ureter. Thus, when the bladder fills and later when it squeezes down to empty, back-up (that is, reflux of urine) is prevented because the valve operates in the same way as when you pinch off a soda straw. This valve-like action is important for several reasons:
- prevents bacteria (that often get into the urine) from getting to the kidneys
- protects the ureters and kidneys from high pressures generated by the bladder during urination
- permits removal of all of the stored urine with a single act of urination, because the bladder urine has nowhere to go other than out the urethra
|Diagram of a normal
|Diagram of ureter tunneling
through the bladder wall
What is vesicoureteral reflux?
With normal urination, the bladder contracts and urine leaves the body through the urethra. With vesicoureteral reflux, some urine goes back up into the ureters and possibly up to the kidneys. Reflux exposes the kidneys to infection. In children, particularly those in the first six years of life, urinary infection can cause kidney damage. The injury to the kidney may result in renal scarring and loss of future growth potential or widespread scarring and atrophy. Even a small area of scarring in one kidney may be a cause of high blood pressure later in life. Untreated reflux on both sides can, in the most severe instances, result in kidney failure requiring dialysis or kidney transplantation.
Why does vesicoureteral reflux occur?
The valve system at the ureterovesical (ureter-bladder) junction may be abnormal:
- In some children the tunnel of the lower ureter through the muscular wall of the bladder may not be long enough. For these children, there is a good chance that growth may provide the necessary difference to allow the valve to work.
- The ureter may enter into the bladder abnormally (usually too much to the side), resulting in a short tunnel. This reflux is less likely to resolve with growth.
The ureter is shown tunneling through the bladder wall.
- If the tunneling of the ureter ends here, reflux is likely.
- If the tunneling of the ureter ends here, reflux is possible.
- If the tunneling of the ureter ends here, reflux is unlikely.
Some children have reflux because of underlying problems such as lower urinary obstruction (such as urethral valves), abnormal bladder behavior (such as uninhibited bladder contractions or hyperreflexic bladders), infrequent voiding, or constipation.
How is reflux evaluated?
Children who are suspected of having reflux should have a renal ultrasound and a voiding cystourethrogram (VCUG). Based on these studies, reflux can be classified into five grades - grade 1 is the least and grade 5 is the worst.
Three Types of Treatments
- Accepted 'conservative' treatment for VUR consists of long-term antibiotic prophylaxis.
- This approach aims to prevent the risk of infection until spontaneous resolution of VUR.
- Avoidance of operative procedures is viewed positively by patients and their parents, although some parents are concerned about potential side-effects of long-term antibiotic use.
- Patients who are not 100 percent compliant risk development of bacterial resistance and breakthrough UTI's.
- 30-40 percent of children with VUR receiving antibiotic prophylaxis for 5 years experience breakthrough UTIs, placing them at risk of renal damage.
- Patients with persistent reflux may require surgery even after receiving prophylaxis for several years.
- Requires yearly VCUG and Renal Ultra-Sound.
- Persistent or severe cases of Grade (4,5) VUR may be corrected with ureteral reimplantation.
- This is an open surgical procedure requiring an overnight hospital stay and urethral catheter for 24 hours.
- High cure rate (99 percent) with a single operation.
- Low complication rate (1 percent for the Cohen Cross-Trigonal technique.
- Ureteral obstruction is one potential complication, requiring re-operation in 0.5 percent of cases.
- Injection of material into the bladder wall to support the submucosal tract of the ureter, thus preventing reflux (the injection is performed under anaesthesia).
- Like surgery, this treatment offers immediate cure, eliminating the risk of renal damage.
- Minor surgical procedure with no overnight hospital stay.
- High immediate cure rate, although a second implantation may sometimes be required.
- Low associated costs, due to short duration of procedure (performed on an ambulatory basis) and minimal side effects.
What about long-term follow-up?
Children with a history of reflux probably should be monitored life-long with measurement of height and weight, blood pressure, and urine analysis. Occasional ultrasound tests will assure that kidney growth is on target for age and size. If kidney function from previous reflux should deteriorate, the pediatric nephrology team can begin appropriate medication and dietary restriction.
What about other family members?
If one child in a family has reflux, there is a 1 in 3 chance of having an affected sister or brother. Because we know that the chances of kidney damage are highest in the first 6 years of life, we think that brothers and sisters in that age range should be studied (with examination, ultrasound and voiding study) even though they may not have been known to have urinary infections.