Posterior Urethral Valves
What are posterior urethral valves?
Posterior urethral valves (PUV), occur in males and are excess flaps of tissue in the posterior urethra, which is the tube that drains urine from the bladder to the outside of the body for elimination. These extra flaps in the urethra block the regular flow of urine out from the body. This can cause damage to the child’s bladder, ureters and kidneys.
The amount of damage that can occur depends on the amount of obstruction in the urethra and how early and quickly the child receives medical intervention. Early diagnosis and intervention, combined with long-term care, provides the best results for patients. Depending on the severity of the PUV, it can be treated with various surgical interventions. Endoscopic incision of valves is the most common surgical procedure. With medical management, most boys with PUV will lead healthy lives and have normal kidney function, bladder function and continence (the ability to control urination).
What causes posterior urethral valves?
PUV are the most common cause of severe types of urinary tract obstruction in children. PUV is a congenital condition, meaning that the child is born with these valves. Valves are thought to develop in the early stages of fetal development. The abnormality affects only males and occurs in about one in 8,000 births. Although the disorder usually occurs by an unknown cause, in some cases it has been seen in twins and siblings, which suggests it may be genetic.
What are the symptoms of posterior urethral valves?
The syndrome may occur in varying degrees from mild to severe. Although each child may experience symptoms differently, symptoms can include:
- Often posterior urethral valves will be suspected from prenatal ultrasounds that show a buildup of urine in a fetus’ bladder and kidneys.
- An enlarged bladder that may be detectable through the abdomen as a large mass.
- Difficulty with urination or inability to urinate.
- Weak urine stream.
- Poor weight gain.
- Urinary tract infection.
- Painful urination.
- Kidney failure.
The symptoms of PUV may resemble other conditions or medical problems. The specialists at the CHOC Urology Center work carefully with each patient to ensure a proper diagnosis and treatment plan.
What medical complications can occur with PUV?
When the extra flaps in the urethra block the flow of urine from leaving the body, the child can experience damage to the bladder, ureters and kidneys. The amount of damage depends upon how early in life the condition is treated and the amount of obstruction in the urethra. Boys who have mild valves will sometimes not be diagnosed until school age. More severe cases are usually diagnosed at a much younger age or directly after birth. Some boys may have their PUV diagnosed during an ultrasound while still in their mother’s womb.
Severe cases of PUV can lead to the following medical complications:
- Poor weight gain
- Severe hydronephrosis
- Vesicoureteral reflux
- Bladder dysfunction
- Urinary retention
- Renal failure
Males with PUV have about a 20% chance of developing kidney failure over their lifetime. The specialists at the CHOC Urology Center work with the patient and family to prevent future damage to the urinary tract and minimize the consequences of the valves. We monitor boys with PUV until adulthood for complications.
How are posterior urethral valves diagnosed?
The severity of the obstruction often determines how a diagnosis is made. Often, PUV are 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 our specialists. In order to properly diagnose PUV, our specialists may order the following tests:
- Renal ultrasound uses a transducer (the wand) that is passed over the kidney and allows us to determine the size and shape of the kidney, and to detect a mass, kidney stone, cyst or other obstruction or abnormalities.
- Voiding cystourethrogram (VCUG) is a specific x-ray that examines the urinary tract and allows specialists to see a direct image of the bladder and a refluxing ureter, if present.
- Cystoscopy is a test that uses a small, flexible tube with a light and a camera lens at the end (cystoscope) to examine the inside of part of the urinary tract.
What is the treatment for posterior urethral valves?
The CHOC Urology Center specialists will determine each child’s treatment based upon:
- Patient’s age, overall health and medical history
- Extent of the abnormality
- Patient’s tolerance for specific medications, procedures or therapies
- Expectations for the course of the abnormality
- Family’s opinion or preference
Treatment for PUV depends on the severity of the condition. Upon initial diagnosis of PUV, 95% of patients undergo a surgical procedure to remove the valve causing the obstruction. During the procedure, a cystopscope (a small telescope with a camera and a light on the end) is inserted into the urethra and the valve is ablated. The extra tissue is cut and trimmed down so that it no longer obstructs the flow of urine. The procedure is minimally invasive.
Some children will require more severe interventions to allow their urine to empty fully, such as the use of a catheter to empty the bladder or a vesicostomy. A vesicostomy is a small opening made in the bladder through the abdomen to allow the urine to flow easily out of the bladder. This is usually closed when the child is older and his urinary tract has improved.
A child may need to use catheters to help regularly empty their bladder. If catheters are needed, our staff will provide caregivers with detailed instructions on how to properly perform the catheterizations.
Medication management is also sometimes used in patients to either help relax the bladder muscle or to prevent urinary tract infections. A member of our team will decide if the child needs medication and discuss medication options with the patient’s family.
Boys with PUV will periodically have blood work done to check their kidney function. Other ongoing tests can include flow rate and post void residuals, renal ultrasounds, VCUGs and sometimes VUDS. (Learn more about common diagnostic procedures used by the urology center.) Children are monitored into adulthood to ensure the best outcomes.
What is the long-term outlook for boys with PUV?
Many children with PUV lead regular lives and are fully continent. Close monitoring by a pediatric urologist throughout childhood helps to ensure the best outcomes and reduce the chances of renal failure.