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Posterior Urethral Valves

By Philip E. Gleason, MD

Posterior urethral valves is the first of several topics which are very specific and specialized diagnoses within Pediatric Urology. These conditions may present and become apparent at any age. In addition, they may present in a variety of ways with different symptoms or findings. Often, however, they are diagnosed fairly early in the child's life and can be some of the more serious conditions diagnosed. As such, they are conditions that are diagnosed, treated and followed-up over longer periods of the child's life, and may affect the child and their families to varying degrees their entire lives. This topic section will present introductory information regarding posterior urethral valves.

Posterior urethral valves occur once in about 6500 male births. It only occurs in boys, not in girls.

It occurs because of valves, or leaflets of tissue, that can obstruct and block the urethra draining from the bladder out through the penis. As such, these valves can block not only the bladder, but also the entire upper urinary tract and system as well including the ureters and kidneys. These may be present throughout in-utero development of the urinary system, and there is often also associated vesicoureteral reflux. In addition, because of the blockage during development of the kidneys, there may be associated renal dysplasia in which the kidney tissue has not have completely formed normally, or may have formed some scar tissue. As such, there may be some decreased kidney function.

Because posterior urethral valves occur throughout in-uterine development, there can be several effects on the child and their development. We have mentioned that the blockage of the urinary system can primarily cause dilation, or hydronephrosis, of the urinary tract and can affect the kidneys. In addition, urine also makes up a lot of the amniotic fluid. Amniotic fluid is important for general development for the child, and in particular is important for pulmonary and lung development in children. Thus, if kidney function and urine drainage and output are affected, this can secondarily lead to decreased amniotic fluid. This can then also secondarily lead to decreased lung and pulmonary development. Severe cases of posterior urethral valves can thus produce kidney and lung failure, know as Potter's Syndrome.

The timing and diagnosis of posterior urethral valves depends on their severity. They can range from fairly severe as we have seen to fairly mild, depending on the severity of the urethral blockage and the bladder's and kidneys response to the blockage.

Very mild PUV may not really cause that much blockage at all. As such, the blockage may not really obstruct the urethra and bladder so much as just irritate the urethra and bladder. In these boys, they may present in older childhood with more of irritative voiding symptoms such as urinary frequency, urgency, wetting and dysuria.