The development of the urinary system starts early in fetal life; separate pieces develop and search each other to come together and form the urinary system. Urine will now be able to leave the kidneys, travel through the ureters and reach the system’s storage tank known as the urinary bladder; from then on urine is carried through the urethra and out of the body. The child’s kidney start working after the 4th month of pregnancy. The fetus then swallows the amniotic fluid in which he lives; its kidneys percolate it and then the fetus urinates inside the amniotic sac, recycling it this way.



In boys, the urethra results from the junction of two separate pieces. The posterior urethral valve is the stenosis, which develops in fetal age at the junction of these two separate pieces. A girl’s urethra is much sorter and develops from a single piece; thus, posterior urethra valves are only present in boys.


In general

This stenosis makes the emptying of the urinary bladder harder. The urinary bladder is a muscular organ, a sort of a bag resembling our heart. The urinary bladder contracts to push out urine out of the body. When there is an obstacle in the emptying process, the muscle works harder to overcome the problem and the bladder’s muscular wall gets thicker. This thickening results to high pressure inside the bladder (intrabladder pressure). High intrabladder pressure can cause either the blockage-stenosis of the ureterobladder junction or vesicoureteral reflux of urine. This thickening of the urinary bladder’s wals as well as the hydroureter and hydronephrosis it causes, are detected by means of ultrasound examination. Consequently, we usually come to a diagnosis of the problem before birth. Some times however, when the stenosis is of a smaller scale, pre-birth diagnosis cannot be achived neither do we encounter an urinary infection. Diagnosis of the problem, in this case, is achieved at a later age, when operational problems of the urinary bladder (urinary incontinence, urinary urgency, urinary infections etc) make their appearance.



The stenosis of the urethra affects both kidneys. When serious, it significantly damages the fetus’ kidneys early on in the pregnancy, which can result to its interruption due to eventual kidney failure. Over evaluation of the problem’s gravity is quite common; hence it is necessary to consult a pediatric urologist before interrupting a pregnancy. Fortunately, we most of the times do not encounter any damage of the kidneys at birth, and when we do so they are usually minor ones so that the child can live a completely normal life.


Dealing with it

In case of prenatal hydronephrosis, the after birth urethrocystography will show if the kid has posterior urethral valves or not. The urethrocystography of a boy, mush always include an x-ray of profile urethra while he urinates. If the urethrocystography is not operated properly, chances are that the diagnosis will not be accurate; the kid might then get into trouble. Starting from his birthday the child must enter a quotidian prophylactic treatment of antibiotics.


Surgical operations

When diagnosis is made before the child’s birth, the operation is performed immediately after the child has left the maternity hospital. Under general anesthesia and with the help of TV-camera control, the operation is performed endoscopically. The child has to stay at the hospital for only one night. It is a delicate operation which must be performed by highly specialized surgeons.

A few years ago many of these kids ended up having kidney failure, whereas today everything can progressively come back to normal after a correct operation.

If the child is underweight and the size of the penis is too small for our endoscopes to enter it, a urinary catheter will be connected to his bladder for a month until he and his penis grow sufficiently.


Frontal urethral valves

Very rarely, the urethra’s stenosis can be situated much further from the urinary bladder, towards the end of the urethra. Those are the valves of the frontal urethra; which present the same symptoms and call for the same treatments as the posterior urethral valves.


X-ray during the miction where we can see the narrowing of the posterior urethra.
Those valves have created left vesicorenal reflux.


X-ray during the miction in a few months old baby.
We can see a very rare case of narrowing of the anterior urethra who has created both sides vesicorenal reflux.

Pediatric Urology
and Endocrine Clinics

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