Most cases of PUJ dysfunction are diagnosed before birth but in some cases it is not diagnosed until the baby has already been born. In rare cases it may be found in an older child.

Tests and diagnosis before birth

Swelling of the kidneys before birth (antenatal hydronephrosis) is usually noticed on an ultrasound scan during your pregnancy.

During routine scans, other things about your baby will also be monitored such as:

• How well they are growing
• How much fluid they have around them in the womb

Other conditions that look like PUJ dysfunction

There are a number of other conditions that might cause hydronephrosis in a baby. These include:

Transient hydronephrosis

Most cases of antenatal hydronephrosis are not serious. The problem may disappear by the time the baby is born, or in the first year or so of life, with no long-term effects.

Vesicoureteral reflux

In vesicoureteral reflux (VUR) (also called vesicoureteric reflux) urine travels back up the tubes from the bladder to the kidneys in the opposite direction to normal.

Vesicoureteric junction Obstruction (VUJO)

In VUJO there is usually a narrow and stiff section of the ureter as it enters the bladder. This causes a hold up of urine passing into the bladder, causing a build-up in the ureter and kidney which become swollen.

Posterior urethral valves in boys

Baby boys born with posterior urethral valves have extra flaps of tissue in the tube that carries urine out of their body. This may cause them to not be able to wee normally, both while growing in the womb and after they are born.

Other conditions that may be seen with PUJ dysfunction include:

Horseshoe kidney

A horseshoe kidney means that, instead of having two separate kidneys on each side of the body, the two kidneys are joined by their lower parts forming a U-shaped or horseshoe kidney.

CHARGE syndrome

Children with a genetic disorder called CHARGE syndrome can be more likely to have PUJ obstruction. If it is known that your child has this disorder, or there are concerns that your child has an anomaly (difference) in another part of their body, they may be referred to a geneticist. A geneticist is a doctor who specialises in genetic disorders.

Tests and diagnosis after birth

There are a number of tests that may be done to look at the structure of your child’s kidneys and how well they are functioning.

Ultrasound

After your baby is born, they will normally have an ultrasound scan, similar to the ones done during your pregnancy. This may confirm that one or both of their kidneys are swollen but won’t generally confirm the exact cause. During this ultrasound, the person doing the scan will measure how swollen your child’s kidneys are. These measurements may determine what type of scan your baby has next.

DMSA scan

This is an imaging test that looks at how well your child’s kidneys are working and checks for any scarred areas. DMSA is short for dimercaptosuccinic acid which is the chemical used in the scan.

MAG3 scan

This scan uses a radioactive tracer fluid to look at the function of your child’s kidneys, to show anything that may be affecting how well they’re draining into their bladder. MAG3 is short for mercaptoacetyltriglycine which is the radioactive chemical used to show your child’s kidneys more clearly on the scan.

Your child may also have blood and urine tests to check how well their kidneys are working.