Urethral Valves

Urethral valves are a birth defect affecting only boys, where extra flaps of tissue block the tube that carries urine out of the body, potentially causing serious damage to the bladder and kidneys if left untreated.

Table of contents

• What are urethral valves?
• Medical identification codes
• Affected parts of the body
• What causes urethral valves?
• How common is this condition?
• Signs and symptoms
• Possible complications
• How are urethral valves diagnosed?
• Treatment options
• Long-term outlook and monitoring

What are urethral valves?

Urethral valves occur when a boy is born with extra flaps of tissue that have grown in his urethra (the tube through which urine exits from the bladder to outside the body). These tissue flaps are not actually valves in the traditional sense, but rather obstructing membranous folds that prevent the urethra from properly carrying urine from the bladder to the tip of the penis and out of the body.^[3]

The most common type is called posterior urethral valves (PUV), where the obstructive membranes develop in the urethra close to the bladder. This is the most common cause of urinary tract blockages in boys.^[1][4] A less common type is anterior urethral valves, though symptoms and care are similar for both types.^[3]

When urine cannot be normally expelled from the body, the organs of the urinary tract may become dilated or swollen. If this dilation occurs, it may cause serious damage to the tissues and cells within those organs. The bladder, ureters, and kidneys can become progressively dilated, which can lead to permanent damage.^[1][3]

PUV, Posterior Urethral Valves, Congenital Obstructive Posterior Urethral Membrane (COPUM)

Medical identification codes

Healthcare providers use specific codes to identify and classify this condition in medical records and for insurance purposes.

Affected parts of the body

Urethral valves affect multiple parts of the urinary system:

• Urethra
• Bladder
• Ureters
• Kidneys

What causes urethral valves?

Urethral valves are congenital, which means boys are born with these extra flaps of tissue.^[3] The abnormality is thought to develop in the early stages of fetal development, believed to occur between the 9th and 14th weeks of pregnancy.^[4][13]

Researchers suspect that during fetal development, the body normally sends signals that tell tissue in the urethra to stop growing or help it decrease in size. In boys with urethral valves, this signal may never get sent or picked up, which causes the tissue to keep growing.^[3]

The exact cause remains unknown, but extra tissue in the urethra near the bladder narrows the passage so urine doesn’t flow through as easily as it should. This disorder usually occurs by chance (sporadic). However, some cases have been seen in twins and siblings, suggesting there may be a genetic component.^[1][2]

How common is this condition?

Posterior urethral valves affect only male infants. About 500 babies born each year have posterior urethral valves, occurring in approximately 1 in 3,000 to 1 in 8,000 live births.^[1][2][4] It is the most common cause of lower urinary tract obstruction in the fetus and in children.^[13]

Signs and symptoms

The severity of symptoms depends on how much the valves block urine flow. Urethral valves occur in varying degrees from mild to severe.^[1] In mild cases, a boy’s symptoms may not surface until the age of 10 years or older. In more serious circumstances, they can present as severe dilation of the kidneys in newborns.^[3]

Due to increased use of prenatal imaging, many cases are now identified before birth through routine ultrasound. Signs that may be seen on a prenatal ultrasound include:^[15]

• Bilateral hydronephrosis (when urine backs up into the kidneys, causing them to swell)
• Thickened bladder wall
• Low amount of amniotic fluid around the baby (oligohydramnios)
• Problems with lung development (pulmonary hypoplasia)

Children who are diagnosed later may have the following signs or symptoms:^[1][2][3]

• Weak or dribbling stream of urine
• Difficulty urinating
• Painful urination (dysuria)
• Urinary tract infections
• Frequent need to urinate
• New onset of urinary incontinence
• Bedwetting or wetting pants after toilet training
• Poor weight gain in infants
• An enlarged bladder that can be felt through the belly

Possible complications

Urethral valves can lead to a broad range of complications, spanning from asymptomatic cases to severe life-threatening conditions.^[4] The degree that urine is blocked determines the severity of urinary tract problems.^[1]

Severe cases can lead to the following medical complications:^[3]

• Respiratory distress
• Hydronephrosis (severe dilation of the kidneys)
• Bladder dysfunction
• Kidney function impairment and increased risk of kidney failure
• Vesicoureteral reflux (when urine flows backwards from the bladder up to the kidneys)

Posterior urethral valves can lead to:^[2]

• Inability to empty the bladder completely (urinary retention)
• Kidney swelling
• Kidney failure

Approximately one-third of patients with posterior urethral valves eventually progress to end-stage renal disease and will require dialysis or transplantation.^[11] The progression of kidney disease may be accelerated during puberty as a consequence of increased metabolic workload placed on the kidneys.^[11]

How are urethral valves diagnosed?

Today, more and more cases of urethral valves are being detected during pregnancy through prenatal ultrasound. This early detection means that a baby’s symptoms can be treated before they become more serious or cause more injury.^[3] Sometimes, a provider diagnoses posterior urethral valves with an ultrasound during pregnancy.^[2]

Once a baby is born, further imaging studies will confirm the diagnosis.^[1] At or after birth, a provider might use one or more of these tests to diagnose urethral valves:

Voiding cystourethrogram (VCUG) is the primary test used to diagnose urethral valves. During this test, a catheter (tube) is placed through the child’s urethra into the bladder. The tube is used to slowly fill the bladder with a solution called contrast. This test lets the provider see how well the bladder fills and empties, and will also show the urethra and any areas of narrowing. The test shows a characteristic tapering of the urethra.^[1][2][5]

Kidney ultrasound can help the provider see any blockages or differences in how the child’s kidneys, bladder, and urinary tract look. Ultrasound will usually show a dilated urethra, bladder, and kidneys. While supportive of the diagnosis, ultrasound alone is not confirmatory.^[2][5]

Cystoscopy uses a small, flexible tube with a light and camera at the end to look inside the child’s urinary tract. Occasionally, confirmation of valves with cystoscopy (direct visualization of valves) is required.^[2][5]

Kidney function tests using blood or urine samples can help determine how well the child’s kidneys are working.^[2]

Treatment options

All children with urethral valves need surgery to remove the blockage.^[12] In newborns, the first step in treatment is to relieve bladder outlet obstruction by placing a urethral catheter. Once the child is stable, treatment to remove the valves can be performed.^[11]

Treatment for posterior urethral valves is usually a procedure to remove or destroy the blockage. The main surgical treatment is called cystoscopic ablation (also called endoscopic valve ablation). This is a type of endoscopic surgery that allows access to the urinary tract without making any surgical cuts. Instead, a small tube with a light and camera (cystoscope) is passed through the urethra. Tiny surgical tools are passed through the cystoscope to cut the valves and remove the obstruction. A provider often does this with fulguration, using electricity to destroy the tissue with heat.^[2][5][12]

Some young children who cannot empty their bladders may need surgery that temporarily helps the bladder drain. Options include:^[12]

• Vesicostomy creates a new passageway that lets urine flow from the bladder through a small opening in the belly. The healthcare provider makes a small opening in the bladder through the belly, which can be fixed at a later time.^[6]
• Catheterization to empty the bladder
• Urethral dilation to widen the urethra

Depending on any other issues, a provider may also treat the child with:^[2]

• Antibiotics to treat infections
• Bladder relaxants (antispasmodics) to make urinating easier
• Dialysis or kidney transplant for kidney failure

In some rare cases, a specialist may perform surgery on the fetus while still in the womb. This is done in very severe cases with low amniotic fluid levels.^[2][13]

Long-term outlook and monitoring

If a child has posterior urethral valves, they will probably need blood tests and ultrasounds to monitor kidney function over time.^[2] Long-term follow-up is crucial for monitoring kidney function, managing bladder dysfunction, and preventing complications such as urinary tract infections and chronic kidney disease.^[13]

There is no one-size-fits-all approach to care. Treatment plans are customized based on several factors, including:^[12]

• Age at diagnosis
• Severity of the blockage
• Potential complications
• Overall health and quality of life

Follow-up schedules vary based on age and severity of any kidney or bladder complications. More frequent monitoring is recommended during infancy and the teen years because children in these two age groups are more vulnerable to kidney damage.^[12]

Bladder dysfunction can persist after valve removal. All male children with antenatal hydronephrosis should undergo voiding cystourethrography shortly after birth to exclude posterior urethral valves.^[11] Adequate caloric intake and protein nutrition are essential to growth, though these may also accelerate the rise in kidney function markers. Kidney dysfunction can be accelerated by recurrent infections and elevated bladder pressures.^[11]

For some patients, transition from pediatric to adult healthcare services is important to ensure continuity of care and optimize long-term outcomes.^[4] With proper treatment and monitoring, many children with urethral valves can lead healthy, active lives.