Posterior Urethral Valves (PUV)
What Are Posterior Urethral Valves (PUV)?
Posterior urethral valves (PUV) are obstructive matter that develops in the urethra, often leading to a lower urinary tract obstruction (LUTO) that restricts the flow of urine. This is a congenital (present at birth) condition, occurring only in boys, and may damage the organs of the urinary tract, including the ureters, bladder and kidneys. PUV are rare, affecting only one or two boys per 10,000 live births.
How Are Posterior Urethral Valves (PUV) Diagnosed?
The condition is typically identified prenatally, during an ultrasound examination. PUV are very rarely first identified after the baby is born.
During the prenatal ultrasound, your doctor may see dilated kidneys and ureters, a thickened bladder wall, and a dilated posterior urethra. They may also be concerned about PUV and kidney dysfunction if the mother shows oligohydramnios (less amniotic fluid than normal) or anhydramnios (no amniotic fluid) on ultrasound.
If there is a high prenatal suspicion for PUV, an urgent renal ultrasound and voiding cystourethrogram (VCUG) will be performed shortly after delivery to confirm the diagnosis.
PUV are suspected if the renal ultrasound shows an enlarged, thick-walled bladder with a dilated posterior urethra. The kidneys and ureters may also be dilated on both sides.
Voiding Cystourethrogram (VCUG)
This test is done after the baby is born and is essential to confirm the diagnosis of PUV. A catheter is inserted into the urethra and fills the bladder with a special dye. X-ray images are taken as the bladder fills, and also as the patient empties his bladder. In children with PUV, the bladder may look different than the normal smooth, round shape. There may be diverticula (a pouch formed when some of the bladder lining pokes through a weak part in the bladder wall) from the bladder, as well as, a dilated posterior urethra.
During the VCUG exam, vesicoureteral reflux (VUR) may also be identified. VUR occurs when urine flows back up the ureter into the kidneys, and is commonly found in boys with posterior urethral valves.
Surgical Treatment Options for Posterior Urethral Valves (PUV)
As soon as the diagnosis of PUV is confirmed with a VCUG exam, your child's urologist will usually recommend surgery. Based on the severity of the situation, one of two surgical options will be chosen:
Posterior Valve Ablation
Prior to surgery, your child will be stabilized in the neonatal ICU, while electrolytes and breathing status are monitored. Once stable, your child will be taken to the operating room where the urologist will cut the PUV and relieve the obstruction.
If the urethra is too small to accommodate the scope used to cut the valves for a posterior valve ablation, the urologist may perform a vesicostomy instead. This surgical procedure diverts the urine directly from the bladder to the skin through a small incision above the pubic bone. Circumcision may be considered to reduce the risk of future infection.
Regardless of which surgical option is performed, your child's kidney function will need to be tracked before and after surgery. For a large percentage of patients, VUR will resolve after the bladder-outlet obstruction is relieved. However, if the obstruction is high-grade or is causing problems, your child may need to be on a low-dose prophylactic antibiotic to prevent a urinary tract infection or kidney infection.
Your child's urologist may also use the medication Oxybutynin to help relax the bladder, as some research has shown that it can improve hydronephrosis (swelling of the kidney) and vesicoureteral reflux (VUR) in children with posterior urethral valves.
Your child's kidney function and urinary system should be monitored after surgery. Kidney function should be monitored, at least once each year, after the post urethral valves and bladder-outlet obstruction have been corrected.
The kidneys and urinary systems should also be observed for dilation. Many boys with PUV also deal with bladder dysfunction, urinary tract infections, or resulting urinary incontinence which may require catheterization as they grow older.
About 20 percent to 50 percent of boys with PUV will eventually face end-stage renal disease (ESRD), requiring either hemodialysis, peritoneal dialysis (through the abdomen), or kidney transplantation.