The urinary system is made up of the kidneys, bladder and ureters (tubes that connect the kidneys to the bladder). The kidneys act as filters removing extra fluid and waste from your blood to make urine. Urine passes from the kidneys into the ureters, which drain into the bladder. When the bladder is full, urine flows out of the body through a tube called the urethra.
The ureters normally enter the bladder at a diagonal angle and have a special one-way valve system that prevents urine from flowing back up the ureters in the direction of the kidneys. If this system doesn’t work, urine can flow back towards the kidneys. This is called vesicoureteric reflux (also known as urinary reflux).
Sometimes vesicoureteric reflux (VUR) can be associated with other 'plumbing' problems in the urinary tract and with small, damaged or malformed kidneys.
Symptoms of urinary reflux
Urinary reflux does not have any symptoms. However, urinary tract infections can cause:
- burning sensation when passing urine
- wanting to urinate more often, if only to pass a few drops
- cloudy, bloody or very smelly urine
- pain in the lower part of the body
- stomach aches
- wetting – new day or night wetting in a child who has been dry
- babies and young children may have poor feeding, vomiting and ongoing irritability.
If your child has any of these symptoms, they should see a doctor so that simple tests can be performed.
Causes of urinary reflux
Some of the conditions that may cause or contribute to urinary reflux include:
- family history of urinary reflux
- physical problems (congenital abnormalities) with the kidney present at birth
- physical problems (congenital abnormalities) with the bladder and the bladder outlet
- bladder stones
- trauma or injury to the bladder
- temporary swelling after surgery (such as kidney transplant).
Most cases of urinary reflux correct themselves
Most children who have reflux do not need treatment, but may need to see their doctor regularly. However, some children who have reflux may be advised to take an antibiotic every day to prevent further urinary tract infections, especially very young children or children with other problems with their kidneys or urinary tract.
Diagnosis of urinary reflux
Urinary reflux is diagnosed using a number of tests including:
- Kidney ultrasound – there are several tests that look at the anatomy of the urinary tract. Most children will have an ultrasound of the kidneys and bladder, which is a painless test that gives your doctor a good look at the kidneys and bladder, but cannot show vesicoureteric reflux. For children who have infections, the tests your child receives will depend on their age, how many infections they have had and how bad the infections are. In children who haven’t had infections, further tests may be needed if the ultrasound is not normal. In order to find reflux, an x-ray called a voiding cystourethrogram (also called a micturating cystourethrogram or MCUG for short) is needed.
- Voiding cystourethrogram (MCU) – a fine plastic tube is placed into your child’s bladder and a liquid is passed through the tube to fill the bladder. This liquid shows up on the x-ray and gives a good view of the bladder. X-rays (normal x-rays or sometimes a nuclear medicine scan or special ultrasound) are then taken as your child passes urine. If the liquid is seen on x-ray to pass up the ureters towards the kidney then your child has reflux. Reflux is graded from grade 1 (mild) to grade 5 (severe). Your doctor will discuss the amount of reflux seen on the x-rays with you and your child.
- Sometimes urinary reflux is diagnosed before birth during an ultrasound scan – the baby’s kidney appears larger than normal due to urine reflux.
Treatment for urinary reflux
Most children who have urinary reflux don’t need surgery. Children who may need surgery include those who:
- continue to get urinary tract infections while they are on antibiotics
- have other complex abnormalities of the urinary tract
- have serious reflux.
Surgical correction of reflux consists of either re-inserting the ureters back into the bladder to make a new tunnel, or injecting special material around the bottom of the ureters. Both of these operations restore a functional backflow valve and successfully prevent reflux. If your child needs surgery, your doctor will discuss the options with you.
Screening for urinary reflux
If a child is diagnosed with urinary reflux, it may be important to test the other members of the family. You should discuss this with your doctor.
Where to get help
- Your doctor
- Kidney Health Australia Information Line Tel. 1800 454 363
Things to remember
- There is a valve at the meeting point between each ureter and the bladder to prevent the backflow of urine into the kidneys.
- Urinary reflux means that one (or both) of these valves is not working properly.
- During urination, the urine travels up the affected ureter to the kidney instead of flowing out of the body.
- In most cases, the valve will correct itself as a child grows and matures.
- In severe cases, surgery may be needed to remodel the valve.
This page has been produced in consultation with and approved by:
Kidney Health Australia
Content on this website is provided for education and information purposes only. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your doctor or other registered health professional. Content has been prepared for Victorian residents and wider Australian audiences, and was accurate at the time of publication. Readers should note that, over time, currency and completeness of the information may change. All users are urged to always seek advice from a registered health care professional for diagnosis and answers to their medical questions.