Vesicoureteral reflux

Structure of Normal urinary tract:

The urinary tract is made up of the kidneys, ureters, bladder and urethra. The kidneys are located high up in the tummy and responsible for filtering waste products from the bloodstream and produce urine continuously. The urine flows down the 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 joins the bladder it travels through the wall of the bladder for a distance creating a tunnel so that a flap valve is created. This valve prevents back flow of the urine into kidneys when the bladder is full or the child is passing urine.  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 normal urinary tract Diagram of ureter tunneling  through bladder wall
Diagram of normal urinary tract Diagram of ureter tunneling
through bladder wall

What is vesicoureteral reflux

With normal urination, the bladder contracts and urine is passed 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 6 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 (injury) and atrophy. Even a small area of scarring in kidney may lead to a high blood pressure later on. Untreated reflux with recurrent infections, in the most severe instances, result in kidney failure requiring dialysis or kidney transplantation.

Why does VUR occur

Most commonly the valve system at the ureterovesical (ureter-bladder) junction may be abnormal and this is called Primary VUR.

  • 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. 

VUR

The ureter is shown tunneling through the bladder wall. 

1-if the tunneling of the ureter ends here, reflux is likely.
 
2-if the tunneling of the ureter ends here, reflux is possible.
 
3-if the tunneling of the ureter ends here, reflux is unlikely.
 
 
Secondary reflux: 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. IN such children, the primary treatment is towards the underlying disease which led to reflux and generally reflux subsides when the underlying condition is treated.
 
Diagnosis of Reflux
 
Children who are suspected of having reflux should have a renal ultrasound and a Micturating or a Voiding cystourethrogram (MCUG or a VCUG). Based on this study, reflux can be classified into five grades - grade 1 is the least and grade 5 is the worst. Mild degrees of reflux have a good chance of resolving spontaneously with age. Chances of resolution with high-grade reflux (grade 4-5, or reflux related to an anatomic problem such as a long-standing obstruction) are much lower.
 
Normal kidney, ureter, and bladder Grade I Vesicoureteral Reflux: urine (shown in blue) refluxes part-way up the ureter Grade II Vesicoureteral Reflux: urine refluxes all the way up the ureter
Normal kidney, ureter, and bladder Grade I Vesicoureteral Reflux:
urine (shown in blue) refluxes part-way up the ureter
Grade II Vesicoureteral Reflux:
urine refluxes all the way up the ureter
Grade III Vesicoureteral Reflux: urine refluxes all the way up the ureter with dilatation of the ureter and calyces (part of the kidney where urine collects) Grade IV Vesicoureteral Reflux: urine refluxes all the way up the ureter with marked dilatation of the ureter and calyces Grade V Vesicoureteral Reflux: massive reflux of urine up the ureter with marked tortuosity and dilatation of the ureter and calyces
Grade III Vesicoureteral Reflux:
urine refluxes all the way up the ureter with dilatation of the ureter and calyces (part of the kidney where urine collects)
Grade IV Vesicoureteral Reflux:
urine refluxes all the way up the ureter with marked dilatation of the ureter and calyces

 

Grade V Vesicoureteral Reflux:
massive reflux of urine up the ureter with marked tortuosity and dilatation of the ureter and calyces

 

Treatment of VUR

Since many children will outgrow their reflux, the usual plan is to follow up carefully and prevent infections in the interim. Regular tests such as VCUG, renal ultrasound, or nuclear voiding cystogram may be done when required. During this follow-up period they are kept on a prophylactic (low-dose) antibiotic to keep the urine free of infection. Any fever or new urinary tract symptoms (such as burning, frequency, urgency, straining, foul odor, bloody urine, or unusual incontinence) may indicate infection and must be promptly evaluated with urine analysis and urine culture. Children who develop breakthrough urinary infections in spite of antibiotic prophylaxis are at risk for kidney damage and may need surgical correction of reflux.

Surgery for Reflux

Correction of reflux is recommended for high grades of reflux, for reflux that fails to resolve, or for patients with breakthrough infections. Options are:

  • Endoscopic injections of bulking agents: A small endoscope called cystoscope is placed into bladder and a thick viscous gel called Deflux is injected into the mucosa under the ureteric opening. This leads to creation of a mound which prevents reflux. Advantages include- no cuts, no pain and no post-op complications. Disadvantages are – not 100% successful, can’t be recommended for high grade reflux, gel is expensive and recurrence rate of 10%.
  • Ureteric re-implantation: Surgical correction of reflux involves recreation of the tunnel and the valve function for the ureteric opening. This can be done via a small incision in the lower part of the tummy or in selected cases laparoscopically. The success rates are more than 95% in properly selected and evaluated patients.

Long term prognosis and follow-up

Children with a history of reflux should probably 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 there is any doubt about scarring or kidney function, the pediatric nephrology is also called in to evaluate and manage.

Family members & siblings

If one child in a family has reflux, there is a 20% chance of having reflux in a 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 and atleast an ultrasound). Also if there is any symptoms suggestive of urinary infection, a VCUG should be done.

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