Before birth

The 20 week antenatal ultrasound scan looks at the baby growing in the womb. In some pregnancies, one or both of the baby’s kidneys hold on to urine, and become stretched and swollen – this is called antenatal hydronephrosis. This is due to the large amount of urine the fetus makes towards the end of the pregnancy, and it usually resolves (gets better) on its own. Sometimes, the swelling continues throughout pregnancy, and this may be caused by a number of conditions, including severe VUR.  

After birth

Some babies with antenatal hydronephrosis are tested for VUR and other kidney conditions after birth. 

In older children, VUR is normally found when looking for other problems, such as a urinary tract infection (UTI). Your doctor will speak with you and your child about the symptoms and do a physical examination of your child. Your child’s blood pressure will also be measured.

Imaging tests

Your child may need one or more imaging tests (scans). These use special equipment to create pictures of the inside of his or her body. 

Ultrasound scan

Your baby or child will probably first have an ultrasound scan to look at the kidneys and urinary system. A small handheld device is moved around your child’s skin and uses sound waves to create an image on a screen.

Diagnosing VUR

Your child may have an MCUG (sometimes called a VCUG). A thin flexible tube called a catheter is passed through your child’s urethra and a dye is put through to reach the bladder. This does not hurt your child. A special X-ray machine takes images (pictures) of your child’s bladder while he or she is passing urine. Another test that may be used instead for older children (who are potty trained) is an MAG3 scan with indirect cystogram. A chemical called MAG3 that gives out a small amount of radiation (energy) is injected into one of your child’s blood vessels – a special gel or cream can be used to stop your child feeling any pain. A special camera takes images of your child’s urinary system as the chemical passes through it. 

Diagnosing reflux nephropathy

Your child may need other scans to check for any scarring on the kidneys (reflux nephropathy).

In a DMSA scan, a chemical called DMSA is injected into a blood vessel. The chemical is taken up by healthy parts of the kidney. A large camera takes images.

Sometimes an MRI urogram is used instead. A special dye is injected into a blood vessel. Your child lies on a bed that passes into the MRI scanner, a large machine with a tunnel. This uses powerful magnets to build up a picture of your child’s urinary system.

Urine tests

A urine test can diagnose a urinary tract infection (UTI) or find protein in the urine (proteinuria).

You, or a nurse will need to collect some of your child’s urine in a small, clean container. A dipstick will be dipped into the urine – this is a strip with chemical pads that change colour depending on what substances are in the urine. The sample may also be sent to a laboratory for more accurate tests.

Blood tests

Your child may need a blood test. A blood test can find out about your child’s kidney function (how well his or her kidneys are working) by measuring the glomerular filtration rate (GFR). A small amount of blood may be taken from a vein, with a needle and syringe. A special gel or cream can be used to help your child stop feeling any pain.  

More about measuring GFR in Blood tests