Urine leaves the bladder through a tube called the urethra, which in boys passes through the penis. Rarely, small membranes form across the urethra in boys early in pregnancy, and they can block the flow of urine out of the bladder. These membranes are called posterior urethral valves and can have life-threatening consequences by causing blockage of normal urine flow interfering with development of the kidneys. If there is abnormal kidney development, there can be abnormal development of the lungs.
The severity of posterior urethral valves can vary widely. Most cases are diagnosed before birth with a screening ultrasound. This condition may be suspected in boys if there appears to be a decrease in the amount of amniotic fluid. Consulting a pediatric urology specialist is always advisable before the baby is born.
In boys who are not diagnosed before birth with posterior urethral valve, sometimes the newborn exam may reveal that the baby’s bladder is distended and enlarged. Other warning signals include a continual dribbling of urine and a weak stream during urination. More commonly though, posterior urethral valve is diagnosed when the boy develops a urinary tract infection with fever and poor feeding. If you notice these symptoms, notify your pediatrician at once.
Posterior urethral valves require immediate medical attention to prevent serious urinary tract infections or damage to the kidneys. If the blockage is severe, the urine can back up through the ureters (the tubes between the bladder and the kidneys), creating pressure that can damage the kidneys.
If your child has a posterior urethral valve, your pediatrician may pass a small tube (catheter) into the bladder to relieve the obstruction temporarily and allow the urine to flow out of the bladder. Then he’ll order X-rays and/or an ultrasound of the bladder and kidneys to confirm the diagnosis and to see if any damage has occurred to the upper urinary tract. Your pediatrician will consult with a pediatric nephrologist (kidney specialist) or nurologist, who may recommend surgery to remove the obstructing valves and prevent further infection or damage to the kidneys or urinary system.