How Are Posterior Urethral Valves (PUV) Treated?

The treatment of posterior urethral valves generally requires surgery. In some infants diagnosed with a posterior urethral valve in the womb, as the bladder fills, there is an incomplete but still some outflow of urine. In such cases, if the amount of amniotic fluid is within the normal range, it is permissible to do only observations of fetus’s condition without any interventions. It is possible because the main purpose of intrauterine surgeries is to restore the normal level of amniotic fluid in order to ensure the normal course of development of fetus’s lungs, thereby increasing its chances for life. Therefore, in cases where even with the diagnosis of the posterior urethral valve, the level of amniotic fluid is normal, there is no need for operations.

As for surgical interventions, the medical community still does not have long-term data on how intrauterine surgeries affect the preservation of infant kidney function and save them from dialysis or kidney transplantation throughout their later life. Despite the fact that the results of experiments conducted on animals show a positive effect of operations on the functioning of the kidneys, as well as the presence of a similar trend in humans, to obtain an accurate answer, the data on this topic still needs to be significantly expanded.

What methods are used for intrauterine treatment of posterior urethral valves?

Vesicoamniotic shunting

Vesicoamniotic Shunting

The main goal of intrauterine treatment of posterior urethral valve is to ensure the proper outflow of fetal urine in the womb, which prevents the lack of amniotic fluid, promotes the development of the lungs, and thus prevents the death of the fetus immediately after birth due to pulmonary insufficiency. The most common solution for restoring normal urination of the fetus is considered to be vesicoamniotic shunting. This type of surgery is performed by applying local or regional (spinal) anesthesia and then installing a vesicoamniotic shunt – all accompanied by ultrasound. The catheter is placed so that one end remains inside the baby’s bladder, and the other remains in the amniotic sac containing the amniotic fluid. This procedure makes it possible for urination to occur through the catheter, not the urethra. Such surgeries are short-term and easy to perform. However, in cases of displacement of the catheter or its blockage, repeated surgeries may be required.

What methods are used for intrauterine treatment of posterior urethral valves?

Laser Ablation

Fetal cystoscopy is a visual examination of the fetal bladder using a 3 mm diameter camera accompanied by ultrasound. For this procedure, the mother is given anesthesia, and the fetus, in turn, is also given anesthesia through the umbilical cord and muscle relaxants (drugs that reduce muscle tone and decrease motor activity).

A visual examination helps the doctor to understand whether the cause of abnormalities in urination lies in the valve of the posterior urethra, or the absence of the urethra (urethral atresia), or the pathological narrowing of the internal lumen of the urethra (stenosis). Thus, fetoscopy allows us to find out the exact cause of the obstruction at the exit of the bladder. In cases where the obstruction is caused by posterior urethral valves, the laser fiber is inserted through another channel with a diameter of 1 mm parallel to the camera channel, after which the valve is removed by the laser, ensuring the normal flow of urine. If the problem is urethral atresia or stenosis, then appropriate treatment planning is carried out. In cases where laser cystoscopy is unsuccessful, it can cause damage to neighboring organs, as well as the formation of fistulas. In such situations, repeated surgeries may be required.

What methods are used for intrauterine treatment of posterior urethral valves?

Vesicostomy, Vesicocentesis, And Fetal Ureterostomy

Surgical operations to ensure the temporary or permanent excretion of urine by creating an external fistula of the bladder, although not common, still take place. Such urinary excretion can and does affect the reduction of pressure in the bladder, but its effect on the normalization of the level of amniotic fluid (a determining factor in the development of the lungs) is questionable. All other types of surgeries, unlike laser ablation and bypass surgery, are invasive and not so widespread in practice. Some babies may also have enlarged urethra inside the bladder. This condition is called ureterocele, and if it is observed during fetal cystoscopy, a procedure to decompress the ureterocele can be performed with a laser.

How successful are intrauterine operations to remove the posterior urethral valve?

It is believed that in the absence of surgery, the chances for life of babies with a diagnosis of posterior urethral valves are approximately 25 percent. Due to the fact that babies remain under the pressure of the umbilical cord in the womb, they die in the womb or at an early stage after birth due to severe lung failure. The data proves that intrauterine posterior urethral valve removal surgeries increase the chances of fetal life by two times. This applies to both vesicoamniotic shunting and laser ablation. Although there is strong evidence that this increases the infants’ survival rate, there is still no evidence of how these surgeries affect the long-term kidney function in infants’ later life. Current data suggests that vesicoamniotic shunting is not effective when it comes to maintaining infant kidney function. With regard to laser ablation, the available evidence indicates that infants who have undergone this procedure have better kidney function than infants who have not undergone any surgical intervention. It is worth noting that all the data regarding the use of these treatment methods is relatively new, and still needs to be expanded. Due to the relatively recent discovery of these methods, patients who have undergone such surgeries have not yet reached the age of 10, 20 and 30 years.