Posterior Urethral Valves Symptoms & Causes

If your son has been diagnosed with posterior urethral valves (PUV), you may have questions and concerns about your child’s health and future, such as:

  • Will my son have normal bladder and kidney functioning?
  • Will he be able to have children?
  • What is the long-term outlook for my son?

At Boston Children’s Hospital, we know how important it is for parents to understand their child’s medical concerns. That’s why we’ve provided answers to commonly asked questions such as these following pages. During your appointment, our doctors will explain your child’s condition and discuss management options with you in more detail.

What are posterior urethral valves (PUV)?

  • PUV are an extra growth of tissue beyond what should normally develop in the area of the urethra, near the urinary bladder.
  • This extra tissue prevents the urethra from doing its job in a normal manner, which is carrying urine from the bladder to the tip of the penis where urine is emptied out of the body.
  • When urine can’t be normally expelled from the body, the organs of the urinary tract (the kidneys, bladder, ureters, and urethra) may become dilated, or swollen.
  • This dilation of the urinary tract organs, if it occurs, may cause serious damage to the tissues and cells within those organs.

How serious is PUV?

  • Just as is the case with many other diseases, there’s a wide spectrum of severity when it comes to PUV. The severity of your son’s PUV depends on the degree of obstruction in his urethra.
  • In mild cases of PUV, a boy’s symptoms may not surface until the age of 10 years or older.  The symptoms in these boys are mild and may include urinary tract infections (UTIs), difficulty urinating or urinary incontinence.
  •  In more serious circumstances, PUV is diagnosed shortly after birth if the newborn presents hydronephrosis (severe dilation of the kidneys).
  • Today, more and more cases of PUV are being detected during pregnancy, as prenatal ultrasounds become more common. This early detection means that a baby’s symptoms, and the posterior urethral valves themselves, can be treated before they become more serious or cause more injury.


What causes PUV?

  • PUV is congenital, which means that children are born with the extra flaps of tissue that causes the disorder, even though it’s not always diagnosed at birth.
  • Parents do not pass PUV down to their child. However, PUV has been seen in twins and siblings, suggesting that there is a possible genetic component.
  • The reason why the tissue in the urethra grows more than it should is unknown. However, it’s believed to occur early on in male fetal development.
  • Normally, the flaps of tissue in the urethra are very small structures. It’s believed that during a fetus’ development, the body sends signals that tell the tissue to stop growing or help the tissue decrease in size.
  • In boys with PUV, this signal is thought to be missing. The signal never gets sent or picked up, which causes the tissue to keep on growing.


Symptoms that may result from PUV often vary in terms of their severity, and range from mild to severe. Therefore, each child experiences symptoms differently. Your son's symptoms may include:

  • an enlarged bladder that may be detectable through the abdomen as a large mass
  • urinary tract infection, or UTI (usually uncommon in children younger than 5 and unlikely in boys at any age, unless an obstruction is present)
  • painful urination
  • weak urine stream
  • urinary frequency
  • bedwetting or wetting pants after the child has been toilet-trained
  • poor weight gain
  • difficulty with urination

Are there any medical complications associated with PUV?

Severe cases of PUV can lead to the following medical complications:

  • bladder dysfunction
  • renal function impairment
  • About 50 percent of boys with PUV will have vesicoureteral reflux (VUR).
  • In 50 percent of the cases, VUR can be treated with endoscopic incision of the valves.
  • The other 50 percent of boys may need anti-reflux surgery, also known as ureteral reimplantation

Is my child at risk for kidney failure?

The risk of kidney failure in a boy with PUV is fairly significant. Kidney failure might present in different stages of the boy’s life: either as a fetus, a neonate, or later on in life. Over the course of their lifetime, boys have a 15-20% chance of kidney failure.