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Urinary Reflux

Urinary reflux is the most common abnormality of the urinary system in new born babies.

Reflux means backward flow of urine from the bladder to the kidney. It is caused by a leaky valve at the end of the ureter, which is the tube joining the kidney to the bladder.

Normally the ureter enters the bladder through a tunnel in the wall and this tunnel forms a valve which prevents urine flowing back up the ureter.

Children with urinary reflux have an abnormal connection of the ureter into the bladder so that the valve does not function.


Medical Term

Urinary reflux is also called Vesico-Ureteric reflux, and is graded from 1-5.

It is found in about one third of all infants and young children who have a urinary tract infection. Urinary reflux makes children retain urine in the bladder and ureter after voiding, where the bacteria multiply and cause infection.

Urinary reflux often takes urine back up to the kidneys, leading to the possibility of kidney infection (Pylonephritis) and permanent kidney damage (scarring) in young children.



  • Fever
  • Poor weight gain
  • Irritability
  • Pain on urination
  • Diarrhoea
  • Strong smelling urine
  • Vomiting
  • Cloudy urine
  • Bed wetting if previously dry
  • Blood in the urine
  • General ill health


However, a child with a urinary tract infection may not show any of these symptoms. In these cases the infection may persist for a long time, or recur frequently which may cause permanent damage to the kidneys. Children who have one infection are likely to develop more infections.

If your child has any one of these symptoms take the child to the doctor. The doctor will arrange a urine test to see if the urine has any germs in it.


Taking a sample of urine

Make sure you have a clean jar. You can get them from your laboratory. For children out of nappies, quickly insert the clean jar into the flow of urine and remove it before the stream finishes.

For boys the foreskin should be gently pulled back before the sample is collected. this reduces the risk of the sample being contaminated. You should not forcefully pull back the foreskin.

For infants and younger children, the urine sample will need to be collected by placing a sterile plastic bag over the genital area.

Your GP or Laboratory nurse will provide you with the sterile containers and help you if you have any problems.

The urine sample should be delivered to the laboratory within two hours or it can be left in the refrigerator overnight (not the freezer).

Urinary reflux is often found in other family members and it appears to be inherited. Reflux occurs in about 20% of the brothers and sisters of a child with reflux.

The valve between the ureter and bladder gets more competent with time and as the child grows. The reflux gets progressively less in many children during normal growth. Most children grow out of reflux between 5-15 years.

Scarring is permanent and can predispose the child to blood pressure problems which may develop at any age.



All infants and children who have a urine infection need more tests to see why they are getting the infections. It is not normal for young children to get urine infections.

Your GP will refer you to a specialist called a urologist to have these done.


Renal ultra sound

This is a harmless and painless investigation. Many women have this during pregnancy. It shows if the kidneys are a normal shape and size and are in a normal position. It will usually show if the flow of urine is obstructed or if kidney stones are present.


Micturating Cysto-Urethrogram

This is using an x-ray procedure to see if the reflux is present There are two ways to see if reflux is present, one uses x-rays to see if an iodine-containing solution has moved up the tubes (ureters toward the kidneys); the other uses pictures to show if a radioactive substance has moved back up towards the kidneys. Both these test are done in a similar way. A tube ( catheter) is pushed into the bladder through the urethra. The bladder is slowly filled with fluid and then pictures are taken. When the x-ray examination is done it is usual for the bladder to be filled until the urine passes back down around the catheter and then the catheter is removed. Pictures will show the structure of the urethra. Some children have a blockage to this tube. It will also show if the urine refluxes back up the ureters, towards the kidneys. This test can be done using a weak radioactive solution, but it does not show up the structure of the bladder very well. It is very sensitive for detecting reflux and is useful for a follow up. The amount of radiation your child is exposed to with this test is usually much less than that of an x-ray.



  • Grade I – Ureter only
  • Grade II – Ureter pelvis, and calyces with out dilation
  • Grade III – Mild dilation of ureter, slight blunting of calyceal fornices
  • Grade IV – Moderate dilation, loss of sharp calyceal fornices
  • Grade V – Gross dilation of ureter and calyces


Other investigations

Intravenous urogram

In this test a substance which contains iodine and can be seen on x-ray, is injected into a vein. Normally iodine passes through the kidneys and into the urine. On x-ray it is possible to see in some detail the size and shape of the kidneys, whether there is any blockage to urine flow from the kidneys and even sometimes the bladder. The Doctor will ask if your child has any allergies as some people are allergic to iodine.

A similar test can be done to see if your kidneys are functioning normally. This test uses a weak radio-active substance attached to a chemical that normally passes through the kidneys. This test may be referred to as a radioisotope scan or scintigraphy.

The amount of radiation that your child is exposed to with these tests is usually much less than an x-ray.


Abdominal x-ray

This will show if there are any stones in the tubes (ureters) leading from the kidneys to the bladder or in the bladder.



This can begin once the diagnosis has been made. The child will be given an antibiotic to take orally (by mouth). This is usually given once a day to stop any infections in the urine occurring.

If a urine infection shows while taking the antibiotic, then they will change the antibiotic as the germs may be resistant to the one your child is taking.

It is important to take a urine sample on a regular basis to make sure that the urine is not infected. Usually the Doctor will ask you to collect these on a fortnightly or monthly basis to check the urine is still OK.

After a period of time – usually a year to eighteen months after your child has been on the antibiotics – the specialist will want to do a repeat Micturating Cysto-Urethrogram to check to see if the reflux has righted itself. If it has, then your child should be able to come off the antibiotics and have no more urine infections.


Surgical treatment

Grades 3-5 may need to be fixed by operating and reimplanting the ureters back into the bladder on an angle that stops the urine from refluxing back up into the kidneys.

Firtsly they will try the antibiotics as above and then if there is no improvement over a couple of years they will operate.

If your child has another infection once they have stopped the antibiotics then the specialist may require them to stay on a maintenance dose of antibiotic to protect the kidneys for a little while longer.


Follow Ups

After a period of a year or longer they will repeat the MCU (micturating cysto-urethrogram) to see if the reflux has disappeared. Once the x-ray results have been checked by the specialist then they will decide if more treatment is needed or if no further treatment is necassary.


This advice is only intended as a guideline and is very general. Please check with your specialist or G.P. if you have any questions relating to your child’s condition.


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