Posterior Urethral Valves (PUV)

What happens

The urethra develops early in pregnancy. In PUV, folds of tissue near the bladder outlet do not form properly and act like a partial valve, blocking urine flow. Because the blockage exists before birth:

• the bladder works harder and its wall thickens
• urine backs up into the ureters and kidneys, causing hydronephrosis
• kidney development can be affected
• low urine output before birth reduces amniotic fluid (oligohydramnios), which can affect lung development

Signs and symptoms

Before birth

• swelling of both kidneys on ultrasound
• an enlarged, thick-walled bladder, sometimes with a "keyhole" shape at the bladder neck
• low amniotic fluid

In newborns and infants

• a weak or dribbling urine stream, or straining
• a swollen belly or a palpable bladder
• urinary tract infections with fever
• poor feeding, vomiting and failure to thrive
• breathing difficulty in severe cases from underdeveloped lungs

In older boys (milder valves)

• daytime wetting or bedwetting
• frequent urination or a weak stream
• recurrent urinary infections

Diagnosis

• prenatal ultrasound findings
• kidney and bladder ultrasound after birth
• voiding cystourethrogram (VCUG): contrast is placed into the bladder through a small catheter, and X-rays during urination show the dilated urethra above the valves and any vesicoureteral reflux
• blood tests: creatinine and electrolytes to assess kidney function
• cystoscopy: a tiny camera confirms the valves, usually at the time of treatment

Treatment

Immediate care after birth

A small catheter is placed in the bladder to drain urine and relieve the blockage. Kidney function, fluids and electrolytes are monitored. Antibiotics may be given to prevent infection.

Valve ablation

When the baby is stable, a pediatric urologist removes the valves with a tiny instrument passed through the urethra (endoscopic valve ablation). If the urethra is too small, a temporary vesicostomy (an opening from the bladder to the belly) may be created first.

Prenatal treatment

In selected severe cases, fetal interventions such as a vesicoamniotic shunt are offered at specialist centers. Benefits remain uncertain and are being studied.

Long-term care

Even after successful valve removal, many boys have ongoing issues:

• bladder dysfunction ("valve bladder"): a thick, poorly emptying or high-pressure bladder. Management may include timed voiding, double voiding, medications, clean intermittent catheterization and, at night, bladder drainage
• kidney monitoring: a significant proportion of boys with PUV develop chronic kidney disease, and some progress to kidney failure needing dialysis or transplant, sometimes in adolescence or adulthood
• urinary tract infection prevention, sometimes including circumcision or preventive antibiotics
• blood pressure checks
• growth monitoring

Outlook

Outlook depends mainly on kidney function in the first year of life; the lowest creatinine level reached in the first year is a strong predictor. Many boys have good long-term kidney function with careful bladder management, while others need kidney replacement therapy later. Fertility may be reduced in some men.

Frequently asked questions

What are posterior urethral valves?

They are abnormal flaps of tissue in the back part of the urethra in boys that partly block urine leaving the bladder. They are present from birth and can affect the bladder and kidneys.

How are posterior urethral valves diagnosed?

Many are suspected on prenatal ultrasound, which shows swollen kidneys and an enlarged bladder. After birth, ultrasound and a voiding cystourethrogram confirm the diagnosis, and cystoscopy is used at the time of treatment.

How are posterior urethral valves treated?

A catheter drains the bladder initially, then a pediatric urologist removes the valves through a small scope inserted into the urethra. Ongoing care manages bladder function and protects the kidneys.

Can boys with posterior urethral valves live normal lives?

Many do, especially with good early kidney function and careful bladder management. Some develop chronic kidney disease and may eventually need dialysis or a kidney transplant, so lifelong follow-up is important.