VUJO: Diagnosis and tests in pregnancy

Most commonly, this problem is first detected during routine ultrasound scans in pregnancy. One or both of the baby’s kidneys may be noted to be swollen on those scans. There are, however, other causes of swollen kidneys and so your baby will need further tests to confirm the exact cause after they are born.

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

  • How well he / she is growing
  • How much fluid is around the baby

Other conditions that look like VUJ obstruction

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

  • 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 on the baby
  • Vesicoureteral reflux Urine travels back up the tubes from the bladder to the kidneys (in the opposite direction it should do normally). This may be associated with symptoms of a urinary infection, bloody or cloudy urine.
  • Pelvi-ureteric junction dysfunction or obstruction A blockage of the urine flow at the area (junction) between the ureter and the pelvis of the kidney. Symptoms can include abdominal or back pain, a mass (swelling) in the abdomen, poor growth, bloody or cloudy urine
  • Posterior urethral valves in boys These are extra flaps of tissue in the tube that carries urine out of the body in males. Babies with PUV may not be able to wee normally – both while growing in the womb and after they are born

VUJO: diagnosis and tests after birth

There are a number of tests that can be done to look at the structure of the kidneys and how well they are functioning. Your child may have some or all of the tests below.


After your baby is born, he / she will normally have an ultrasound scan, similar to the ones done during your pregnancy. This may confirm that one or both kidneys are swollen but won’t generally confirm the exact cause. During this ultrasound, the person doing the scan will take some measurements of how swollen the kidney drainage systems are. These measurements may influence what type of scan your baby has next.

DMSA scan (Dimercaptosuccinic Acid)

This is a type of radionucleotide scan. This means that a substance that gives out a type of radiation called gamma rays is injected into the blood stream. This substance is taken up by the kidneys and a special camera takes some pictures. This allows us to see how well the kidneys are functioning.

MAG3 scan (mercaptoacetyltriglycine)

This is another type of radionucleotide scan. In this scan a substance called mercaptoacetyltriglycine is injected into the blood stream. It is also linked to a substance that gives out a type of radiation called gamma rays. It is taken up by the kidneys and then a special camera takes pictures. This type of scan gives us information on how well the kidneys are functioning, but also on how well urine is draining from the kidneys down into the bladder.

Urine tests

You, or a nurse, would need to collect some of your child’s urine in a small, clean container for a urine test. 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

As well as various scans, your child may have some blood tests. This gives an idea of how well the kidneys are working.

VUJO treatment before and after birth

Before birth

In most cases, no treatment before birth is needed. The delivery may need to take place at a centre where urgent surgery could be undertaken if it were needed, but this is rarely required.

After birth

This depends on findings from the antenatal ultrasound scans and tests after birth. In most cases, babies can be discharged home a short time after birth. Rarely, babies need to be moved to a neonatal unit, an area of the hospital for newborn babies, for monitoring and treatment.

Preventing and treating urinary tract infections (UTIs)

Some babies may be at higher risk of urinary tract infections (UTIs). If your baby is found to have hydronephrosis during your pregnancy then after birth, he / she is likely to be prescribed some antibiotics. These are sometimes referred to as prophylactic antibiotics. This means that a low dose of antibiotic is given every day to prevent urine infections. These may be stopped later on the advice of your doctor if the scans that are done are reassuring.


If the kidney scans show that the kidney and / or ureter is very swollen or not working well then your child may be referred to a paediatric urologist (a surgeon specialising in operations on the urinary system in children). They will consider whether an operation is needed. An operation may also be considered in older children if they have VUJO and have symptoms

Indications for surgery include urinary tract infections; increasing or severe dilatation (swelling); and decreased kidney function.

When intervention is needed a urologist may suggest one of several different options:

Stent insertion

A stent is a plastic tube from the bladder to the kidney which helps drainage of urine. A stent is not permanent, but may either be used to allow more time for your child to grow before further treatment or until the condition has resolved. A stent may be performed using a telescope passed in to the bladder through the urethra under an anaesthetic.

Ureteric re-implantation

Sometimes a section of the ureter may need to be removed and the ureter re-implanted into the bladder. Depending upon the size of child this may be performed by a small cut (incision) or laparoscopically (keyhole surgery). Your surgeon (urologist) will be able to work out which would be best for your child if this is needed.

Diversion / cutaneous distal ureterostomy

In some cases, it may be necessary to divert the ureter from the bladder to the skin forming a stoma (opening on the skin) for urine to drain freely into the nappy. This would normally be temporary, and once the child has grown (usually beyond 12 months of age) the ureter would be re-implanted into the bladder.

Your child should be able to do all of the things that other children their age do. Your child should be able to go to nursery and school, play with other children and stay active.

VUJO follow up

Your child will be followed up by healthcare professionals, usually at a hospital. This may be a paediatrician (a children’s doctor), a paediatric nephrologist (a specialist in kidney care) or a paediatric urologist. Your child will have regular monitoring scans usually every 3-6 months over the first few years of life, although this may vary slightly in different hospitals.

Long-term effects

In most babies and children, the degree of swelling is mild, and doesn’t progress over the first few years of life. At this point, scans will stop and nothing will need to be done unless your child developed symptoms. A very small number of children develop long-term problems with their kidneys and will need specialist follow-up throughout life.

Will it happen in future pregnancies?

PUJ dysfunction is not a condition that is inherited. This means that it is unlikely that a future pregnancy will be affected. However, if you have any concerns then speak with your doctor for more information.

Further support

This can be a difficult and stressful experience for you and your family. If you have any concerns or need additional support, speak with your doctor or nurse.

More information

  • Antenatal hydronephrosis

    While a baby is growing in the womb, one or both kidneys hold on to urine and become swollen. This may be short-term or may be caused by another problem.

  • Tests and diagnosis

    Find out more detail about some of the tests used to diagnose or investigate kidney conditions.

  • Urinary tract infection (UTI)

    Urinary tract infections happen when germs get into the urine (wee) and travel into the urinary tract.