PUV is one type of bladder outlet obstruction – these extra flaps of tissue block (obstruct) urine flowing out of the bladder and through the urethra. This can cause complications in a newborn baby.

Once the PUV are confirmed, they need to be removed by surgery. Some boys have no symptoms or complications after this. A few boys have some problems in their bladder and/or kidneys – though these may not happen until later in life. 

Newborn babies 

The antenatal ultrasound scan cannot diagnose PUV, but can show signs of any problems that may be caused by an abnormality such as PUV. Your doctor will let you know as much as possible about what to expect when your baby is born.

PUV rarely causes any problems during pregnancy or in childbirth.

Antenatal hydronephrosis

PUV may be a cause of antenatal hydronephrosis, a common problem in pregnancy. One or both kidneys hold on to urine, and become stretched and swollen. Antenatal hydronephrosis may get better at a later stage in the pregnancy, but your doctor will check how your baby is affected.

Breathing difficulties

Occasionally, PUV can stop the lungs from fully developing. These babies need extra support to help them breathe while their lungs get better.

This happens when PUV cause there to be less amniotic fluid (or liquor), the fluid that babies float in when growing in the womb, than usual.

In extreme and rare cases, the lungs do not develop enough for the support to help, and the baby dies before, or shortly after birth.

Read more about how PUV affects the lungs

While your baby is growing in the uterus (womb), he floats in a clear liquid called amniotic fluid (or liquor). This protects your baby from getting hurt from the outside and helps his lungs mature so he is ready to breathe after birth.

The baby swallows and “breathes in” the amniotic fluid. When the kidneys develop, they start making urine. The baby passes the urine out, adding to the amount of amniotic fluid. If the baby cannot pass urine, there is not enough amniotic fluid – this is called oligohydramnios. 

In serious cases, this can stop the lungs fully developing – this is called pulmonary hypoplasia. These babies are not able to breathe properly after birth, and will need immediate and special treatment. In extreme and rare cases, the lungs do not develop enough for the treatment to help, and the baby dies shortly after birth. 

Other problems 

PUV may happen with other anomalies or abnormalities in the urinary system – one or both kidneys or ureters may not develop properly. This varies from mild to very severe.

In some cases, the kidneys do not work as well as they should – there is reduced kidney function. The first treatment is to drain urine from the bladder. In many babies, the kidney function will get better after this. 

Sometimes, the kidney function does not get better. In others, the kidney function slowly gets worse as the child gets older. Your child will need follow-up appointments to check his kidney function. 

Kidney failure 

Occasionally, babies or children have kidney failure, when their kidneys can no longer support their body. It is not usually possible to know whether and when kidney failure will happen. It may be:

  • at birth – this is very rare
  • during infancy or early childhood 
  • during puberty or the start of the teenage years, when children go through a growth spurt and the smaller kidneys are no longer able to work for the bigger body.

Babies and children in kidney failure need specialist treatment. 


Problems passing urine

Boys with PUV often have problems when passing urine, such as wetting the bed more than usual, feeling pain when weeing, weeing less often or having a poor stream of urine.

However, these symptoms are common, and most young boys with these issues do not have PUV. 

Urinary tract infections

Boys with PUV may be more likely to get urinary tract infections (UTIs) – when bacteria (germs) get into the urine and cause an infection, usually in the bladder. Babies and children with UTIs may become irritable, have a fever, have pain on weeing, feel sick or be sick, or have diarrhoea.

Occasionally the bacteria that cause UTI travel all the way up to the kidneys, where they cause a more serious infection and illness – this is called pyelonephritis. If not treated, this can cause damage to the kidneys. 

UTIs are treated with medicines called antibiotics, which kill the germs. Some boys with PUV get UTIs that keep coming back, even after treatment – these are called recurrent UTIs.

If you think your child has a UTI, seek medical advice.


PUV may cause vesicoureteric reflux (VUR). In VUR, some urine refluxes (goes back up) towards, and sometimes into, the kidneys. These children usually only need treatment if they get UTIs.

Infection in the blood

In some boys with PUV, a UTI can lead to a more serious infection in their blood – this is called septicaemia. Children with septicaemia are admitted to hospital for a few days, and treated with intravenous (IV) antibiotic medicines, which are given with a needle.