Posterior Urethral Valves
What are posterior urethral valves (PUV)?
PUV is an abnormality of the urethra, which is the tube that drains urine from the
bladder to the outside of the body for elimination. The abnormality occurs when the
urethral valves, which are small leaflets of tissue, have a narrow, slit-like opening
that partially impedes urine outflow. Reverse flow occurs and can affect all of the
urinary tract organs including the urethra, bladder, ureters, and kidneys. The organs
of the urinary tract become engorged with urine and swell, causing tissue and cell
damage. The degree of urinary outflow obstruction will determine the severity of the
urinary tract problems.
What causes posterior urethral valves?
PUV is the most common cause of severe types of urinary tract obstruction in children.
It is thought to develop in the early stages of fetal development. The abnormality
affects only males and occurs in about 1 in 8,000 births. This disorder is usually
sporadic (occurs by chance). However, some cases have been seen in twins and siblings,
suggesting a genetic component.
What are the symptoms of posterior urethral valves?
The syndrome may occur in varying degrees from mild to severe. The following are the
most common symptoms:
An enlarged bladder that may be detectable through the abdomen as a large mass
Urinary tract infection (usually uncommon in children younger than age 5 and unlikely
in boys at any age, unless an obstruction is present)
Weak urine stream
Bedwetting or wetting pants after the child has been toilet trained
Poor weight gain
Difficulty with urination
The symptoms of PUV may look like other conditions or medical problems. Always consult
your child's doctor for a diagnosis.
How are posterior urethral valves diagnosed?
The severity of the obstruction often determines how a diagnosis is made. Often, PUV is
diagnosed by fetal ultrasound while a woman is still pregnant. Children who are diagnosed
later often have developed urinary tract infections that require evaluation by a doctor.
This may prompt your doctor to do further tests, which may include:
Abdominal ultrasound. A diagnostic imaging technique that uses high-frequency sound waves and a computer
to create images of blood vessels, tissues, and organs. Ultrasounds are used to view
internal organs as they function, and to assess blood flow through various vessels.
Voiding cystourethrogram (VCUG). A specific X-ray that examines the urinary tract. A catheter (hollow tube) is placed
in the urethra (tube that drains urine from the bladder to the outside of the body)
and the bladder is filled with a liquid dye. X-ray images will be taken as the bladder
fills and empties. The images will show if there is any reverse flow of urine into
the ureters and kidneys.
Endoscopy. A test that uses a small, flexible tube with a light and a camera lens at the end
(endoscope) to examine the inside of part of the urinary tract. Tissue samples from
inside the urinary tract may also be taken for examination and testing.
Blood test. A blood test may be done to assess your child's electrolytes and to determine kidney
What is the treatment for posterior urethral valves?
Your baby’s health care provider will figure out the best treatment based on:
How old your baby is
His or her overall health and medical history
How sick he or she is
How well your baby can handle specific medications, procedures, or therapies
How long the condition is expected to last
Your opinion or preference
Treatment for PUV depends on the severity of the condition. Treatment may include
Supportive care. Initially, treatment may focus on relieving your child's symptoms. If your child has
a urinary tract infection, is dehydrated, and/or has electrolyte irregularities, these
conditions will be treated first. Your child may have a catheter placed in his bladder
(a small hollow tube that is inserted into the penis through the urethra and is threaded
up into the bladder). Your child may also receive antibiotic therapy and intravenous
Endoscopic ablation. After the initial management, a urologist (a doctor who specializes in the disorders
and care of the urinary tract and the male genital tract) may see your child. The
urologist may perform a procedure called an endoscopic ablation. During this procedure,
the urologist will insert an endoscope, a small, flexible tube with a light and a
camera lens at the end. With this tube he or she will examine the obstruction and
remove the valve leaflets through a small incision.
Vesicostomy. In certain situations, a different procedure called a vesicostomy may be required.
A vesicostomy is a small opening made in the bladder through the abdomen. Usually
this opening is repaired at a later time when the valves can be cut more safely.
Nearly 30% of boys with PUV may have some long-term kidney failure that may need to
be addressed. The prognosis for PUV improves when detected early.