Obstruction of the lower parts of the urinary system of the fetus is diagnosed with a probability approximately equal to one case per 5,000-10,000 infants. This disease, which is more common in male infants, manifests itself as urethral atresia, urethral obstruction, or most often as a posterior urethral valve (RCD). The inability to properly excrete urine causes a lack of amniotic fluid, which causes abnormalities in the development of the baby’s lungs, which in turn causes most babies to die due to lung failure immediately after birth, even when they manage to survive in the womb. A significant number of infants experience distress or death due to compression by the umbilical cord in the womb. The probability of death in the absence of treatment in such cases is approximately 90%.
The stagnation of urine in the upper parts of the urinary system due to deviations in urination negatively affects the development of the kidneys. Therefore, even infants who manage to survive, in the absence of intrauterine treatment, will require dialysis or kidney transplantation in later life.
Ensuring the proper flow of fetal urine in the womb (for example, using vesicoamniotic bypass catheters, Figure 1) promotes proper lung development, which prevents a lack of amniotic fluid. This increases the chances of the fetus’s life by about 4-5 times (from 10 percent to almost 50).
With the development of technology, it has become possible to recognize and treat problems with obstruction by penetrating the fetal bladder with a camera. Using a fetoscope with a thickness of approximately 2.2 millimeters (Figure 2) inserted into the fetal bladder, it is possible to remove the posterior urethral valve (PUV) with a laser or liquid.
Figure 2. Taken from Quintero RA 1995.
Despite the fact that this technique is new, its results seem to be very satisfactory. According to experts, the chances of fetal life after the installation of vesicoamniotic bypass catheters are approximately 50 percent, while the same indicator in the case of fetoscopy is 70-75 percent. Despite all this, it is still not clear how much these procedures help protect the baby’s kidneys.