Patient Education
There are 2 kidneys - each has a pelvis, a ureter that opens in the bladder. Normally, the flow of urine is from above downwards only. In some children, there may be in addition, a flow of urine from below upwards into the ureter and the kidney- this is called Reflux of urine.
Reflux of urine has been known to cause a lot of major problems if undetected and hence untreated. Some of these problems are easily treatable by oral medications, but, some may require an operation to correct the abnormality.
Reflux is basically of 2 types i.e. Primary and Secondary.
Primary reflux is one in which there is no abnormality in the rest of the urinary tract, except an abnormal junction of the ureter and the bladder. Usually, the ureter does not join the bladder thru a hole - but, a part of the ureter has a submucosal tunnel thru which is passes before opening in the cavity of the bladder. This means after entering the bladder on the outer side, it goes between the muscle and mucosal(innermost layer) of the bladder. The length of the tunnel is about 3 - 4 times the diameter of the ureter. This submucosal tunnel acts as a flap valve that gets compressed as the bladder fills up with urine and prevents the urine from the bladder going up into the ureter, at the same time it allows the urine from the ureter to enter the bladder. In some children, if the submucosal tunnel length is too short or the bladder muscle support is inadequate, the valve action cannot occur efficiently and reflux can occur.
Figure 2: Primary reflux
Secondary reflux occurs in those children where the junction of the ureter and the bladder is normal, but, there are high pressures in the bladder and the backpressure can allow the reflux of urine into the ureter(s). The high pressures in the bladder may be due to an obstruction at the neck of the bladder, or in the urethra from where the urine is ultimately expelled out of the body. The high pressure in the bladder is transmitted backward and can cause reflux. In a few children, there may be damage to the nerves supplying the bladder, and even less quantity of urine may generate very high pressures and lead to reflux. Therefore it is important to know the cause of the reflux and then treat the cause after a proper investigation.
Figure 3: Urethral valves with secondary reflux
Symptoms:
which make one suspect presence of reflux in a child are very common, non-specific, and subtle. The doctor must have suspicion and order investigations to prove the presence of the reflux. In a young infant below 1 year age, there may be fever and urinary infection; or may come with not thriving well - always ill, not putting on weight, etc. In an older child, there may be recurrent urinary infections occurring every month with or without fever each time. There may be urinary symptoms like difficulty in passing urine, burning, dribbling of urine, poor stream of urine, and straining to pass urine. Some children may have recurrent abdominal pain more at the back or in the flank. Reflux of long-standing and not diagnosed nor treated - may cause a lot of complications. The damage is mainly to the kidney and its function and part of the damage are permanent, the part is reversible depending on how early the diagnosis and therapy have begun. The effects of the reflux will spell out how the damage occurs. Reflux of urine can occur when the child's bladder begins to fill up with urine. Urine goes up into the ureter, additionally, when the bladder is full and the child is straining to pass urine, once again more urine goes up into the ureter. This urine is over and above the normal urine that is formed within the kidney and is coming down normally. Thus, the amount of urine in the ureter is more than normal and in order to accommodate the excess volume, the ureter dilates stretches. This will increase with time and more volumes of refluxed urine. The urine in the ureter is now stagnant and will enter the bladder after the child has passed urine and will remain there until the child wishes to pass urine again. This may be a period of hours or more. Part of the stagnant urine may again go up in the ureter and stagnate further. Stagnant urine is ideal for getting infected. Thus the child is given treatment for the urinary infection, then the antibiotic is stopped, but the process of reflux continues and after a lapse of a few days or weeks, the infection recurs and the cycle goes on. Reflux has been graded from 1 to 5. Higher the grade of reflux, the higher the urine goes up and into the kidney tissue due to the high pressure. Reflux pressure and the infection together hit the kidney substance and deposit the bacteria within the kidney tissue to cause an infection called Pyelonephritis. This infection can damage the kidney and if left untreated or incompletely treated, may lead to permanent damage to the kidney on one or both sides and finally lad to renal failure which response to Dialysis and later a renal transplant. Pyelonephritis can also be a cause of high blood pressure due to various mechanisms, and in all children will lead to a stoppage of growth of the kidney in all dimensions.
Investigations:
are done based on suspicion and the most important 2 investigations are Ultrasound(USG) of the kidneys, ureters, and bladder; followed by a Voiding Cysto Urethrogram(VCU).
The USG will show the shape, size thickness of the kidneys, presence of dilatation of the ureters, and the bladder wall thickness, residual urine, etc.
The VCU is the next investigation wherein a small tube is passed into the urethra of the child up to the bladder and the bladder is filled with a contrast liquid that is seen as white on an x-ray picture. When the bladder is full one x-ray is taken to look for the shape, size of the bladder, any reflux is present can also be seen and graded. Next, the tube is removed from the bladder and the child is asked to pass urine and a second x-ray is taken as the child is passing urine. This will show the presence of reflux if it occurs only during straining; it will also show the shape and size of the urethra, any obstruction at the bladder neck, or in the urethra that may be the primary cause.
Neither of these investigations tells us the individual function of the kidneys which is essential to know before therapy is begun. This will act as a baseline for later studies to show improvement in function after proper therapy or may show no improvement that may indicate permanent damage has already occurred. This can be done by doing a Radio Nuclear study called DMSA Scan of the kidneys. Here, the radioactive material is injected into the child intravenously and the pictures are taken at intervals and charted. This investigation will tell the individual function of each kidney (normal should be 50%). This will also show non-functioning areas of the kidney as "cold" areas suggesting damage to that part of the kidney. The more the cold areas, the worse is the prognosis, and the lower the percentage function of the kidney, the worse is the prognosis. Serial Scans will show improved function if the treatment is successful and others may show no change in percentage or may even show a falling percentage leading to renal failure.
Treatment:
Primary reflux depends on the severity, the time of diagnosis(age), and kidney function at the time of diagnosis. Certain basic principals are followed in therapy: one is that reflux by itself is not harmful or dangerous, but, together with infection can cause severe renal damage; secondly, reflux that is picked up early will have caused less damage than one picked up later - this is because reflux has been present since birth; and thirdly, reflux is known to decrease in grade and even disappear with increasing age of the child, so if we wait for an adequate time without allowing infection to occur, there may be no reflux after a few years later. The last and most important principle is to prevent infection and reflux may take care of itself. Thus the therapy for grade 1 - 3 reflux in children with adequate renal function is the prevention of infection: this is done by giving a long term, low dose antibiotics to the child for a period of 3 - 4 years under proper supervision and regular check-ups The indications for change in therapy in these children are - urinary infections despite regular antibiotics if a grade of reflux is 4 - 5 if kidney function is severely affected to start with. The only alternate therapy in these cases is the surgical correction of the reflux. Surgery for reflux is called reimplantation of the ureter into the bladder. This is a very major surgery where the ureter is disconnected from the original position, and a fresh tunnel is made within the bladder and the ureter is taken thru this and sutured to the bladder at a different position. The new tunnel must be at least 3 - 4 times the diameter of the ureter to avoid reflux postoperatively. Tubes are kept to drain the urine from the kidneys directly in the ureter. These tubes may be removed after 10 days. The child stays in the hospital for 10 - 12 days before being sent home after the removal of all sutures.
Complications:
associated with this surgery are infection of the main wound, leak of urine around the tubes instead of thru them, the bladder that had been opened for the operation may leak urine outside. Late complications of this procedure are recurrence of the reflux if the tunnel length is inadequate, inappropriate, or due to infection damage; the other is narrowing at the new junction of the ureter and the bladder leading to obstruction of urinary flow and dilatation of the ureter with back pressure on the kidney and damage.
The therapy of secondary reflux is a natural treatment of the basic cause like obstruction distal to the bladder, abnormal bladder function treatment with specific drugs. In most cases, therapy of the primary cause and patience will allow the reflux to subside on its own and no specific therapy is required. If the reflux persists or its complication occurs then it will be necessary to treat the reflux also as has been just described.