This is the sixth installment on hydrocele. Posterior urethral valves, a very niche topic that affects about 1 in 6,000 male babies, are also seen almost exclusively in boys and only rarely in girls in medical journals, so parents of girls can skip it. Both kidneys produce urine, which is collected in the renal pelvis and then passes through the ureter into the bladder, which is a temporary storage place for urine. Urine entering the bladder is not supposed to go back into the ureter. When instructed to do so, the bladder forceps contract while the bladder sphincter relaxes so that urine can be expelled through the urethra. Above: The structure of the urinary system, which you are probably already familiar with. As an in-depth science, it is necessary to continue with the male urethra. Look at the diagram below: Diagram of the male urethra Coming down from the bladder is the prostatic part of the urethra; further down is where the urethra passes through the urogenital diaphragm, called the membrane, and the prostatic and membrane parts are part of the posterior urethra. The prostate and the membrane are part of the posterior urethra. The bulb and the spongy part are part of the anterior urethra. The urethra is not in fact so straight, see the following picture: above: side view, the male urethra has two curves. But the cystoscope is straight, and it takes skill to pass the straight cystoscope through the curved urethra into the bladder. It still doesn’t make sense where the posterior urethral flap is. I couldn’t really find a picture to my liking, so I had to draw one myself (please don’t judge the art level). See the picture below: Top: The posterior wall of the prostate part of the urethra has a protruding structure called the seminal caruncle, where the opening of the vas deferens and ejaculatory ducts is located. The picture on the left is a normal structure without a posterior urethral valve, while the picture on the right has a posterior urethral valve. The posterior urethral valve is just below the seminal frenulum and continues on both sides to form a pair of sails that can block the flow of urine through. Above: This is the true face of the famous posterior urethral valve! There is one on each side as shown by the white marker. Ninety-five percent of the posterior urethral valves are like this (so-called type I), and 5% are ring-shaped (so-called type III), also in this position. Don’t really underestimate this small pair of posterior urethral valves, you know, they can be quite harmful! Above: posterior urethral valves are essentially a congenital obstruction of the posterior urethra. When there is an obstruction in the posterior urethra, it is easy to understand: urination will not flow smoothly, the urethra above the obstruction site will expand, the internal pressure in the bladder will rise, some places in the bladder will thicken, some will protrude outward in weak places, the bladder will be uneven (see below), urine will also reflux into the ureter, the ureter and renal pelvis will then expand, it will be accompanied by recurrent urinary tract infections, and the kidneys will develop “reflux nephropathy”, which can also lead to chronic renal failure. This is a chain of processes that should be easy to understand. Above: After urethral obstruction, trabeculae (raised part) and small rooms (depressed part) are formed in the bladder, causing the unsmoothness of the inner bladder wall But just understanding the above is still not enough, I will add one more line: After urethral obstruction caused by posterior urethral valves, urine may enter the vas deferens through the opening of the vas deferens up to the epididymis, repeatedly causing epididymitis. Inflammation of the epididymis – epididymal abscess – abscess penetrating the scrotal skin – scrotal fistula formation, this sequence of processes can be understood, right? But that’s not enough, the dangers of posterior urethral valves are truly too numerous to mention. The posterior urethral valve does not grow after birth; it is either there or it has already formed during the embryonic period. The fetus is a very special time and urinary obstruction can cause renal hypoplasia (early pregnancy only) or hydronephrosis (mid to late pregnancy), obstruction of the posterior urethra can severely affect fetal urination, and decreased amniotic fluid can in turn cause fetal lung hypoplasia. All of these can be fatal. Therefore prenatal intervention may be necessary for some severe cases. Top: Posterior urethral valves during fetal life. The vesicoureter was dilated and both kidneys were dysplastic in this case, which was fatal. Boys who are not fatal in the fetal period and are able to be born with severe manifestations of renal insufficiency such as respiratory distress and electrolyte disturbances can still be life-threatening as well. Others may show difficulty urinating, distended bladder, and bilateral hydronephrosis after birth. Newborns are likely to require emergency treatment. Other children will quickly develop urinary tract infections. Older children often present with recurrent urinary tract infections, recurrent epididymitis, difficulty in urination (dribbling, weak urine lines, etc.), bilateral hydronephrosis ureteral dilatation, and growth retardation, among others. The severity of the damage depends on the severity and duration of the obstruction. The more severe it is, the earlier it manifests, and individually it may even be detected after the age of 10. In boys with the above-mentioned manifestations, if the ultrasound suggests bilateral hydronephrosis, bilateral ureteral dilatation (it is not excluded that some individuals are unilateral), bladder wall thickening or residual bladder urine (the bladder should be empty after urination, if there is still urine left, it is called residual urine), all should be considered as possible posterior urethral valves. Cystourethrography can be very helpful in the diagnosis. See the following two images: Top: bilateral vesicoureteral reflux, bilateral ureteral dilatation, and gross bladder wall Top: during urination, vesicoureteral reflux, gross bladder wall, and dilated posterior urethra as indicated by the arrow, suggesting the presence of a posterior urethral valve Cystoscopy and microscopic electrodesiccation of the valve is the single most important treatment, and the procedure is performed under general anesthesia. The cystoscope is inserted into the urethra through the urethral orifice, allowing the inner surface of the bladder and urethra to be seen on the monitor, and if the presence of a valve is confirmed, cautery is performed to destroy the valve structure. Does that destroy the valve and it’s all over? The answer is no. Close follow-up is still needed after surgery, with follow-up cystourethrography if necessary, and possibly even another cystoscopy and another valvuloplasty. All the surgeon can do is unclog the drain. It is also unlikely that the changes in bladder, ureter, and kidney morphology already caused by the posterior urethral valve will completely disappear with the cautery of the valve. As well, impairment of bladder function, vesicoureteral reflux, and functional impairment of the kidneys may persist over time. Risk factors for urinary tract infection also remain. Eventually about 20% will still develop chronic renal failure. Therefore early diagnosis and early treatment is the key. For post-surgical patients, long-term follow-up and necessary treatment is still a long way to go. Incidentally, the anterior urethra can also have valves, but in an irregular position and morphology, while the symptoms and consequences are similar to those of the posterior urethral valves. In some cases, the two may even appear together, as shown in the following figure: posterior urethral valve superior anterior urethral valve