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Fetal Urinary Obstruction - LUTO

  • We are one of the teams with the most surgical experience in the world, with more than 2000 interventions performed, the shortest surgical times reported in the medical literature and, consequently, very low rates of complications.  
  • We are one of the few centres in the world that offer treatment for fetal lower urinary tract obstructions (LUTO) and therefore one of the most experienced. 
  • As a pioneering development centre in fetal surgery, we continuously research and incorporate technologies that further improve accuracy during surgery. 
  • Through a pioneering system of three-dimensional simulation of fetal urinary tract obstruction we can visualize and print 3D models that allow us to simulate and practice the intervention before performing it, minimizing the necessary surgical time and the associated risks. 
  • We are a multidisciplinary team, which allows us to approach surgery in a comprehensive way: from the choice of the best strategy to individualized postnatal follow-up. 

Fetal Urinary Obstruction

What is fetal lower urinary tract obstruction (LUTO)?

Lower Urinary Tract Obstruction (LUTO) is a malformation of male fetuses that consists of the obstruction of the urethra at the level of its exit from the bladder. The urethra is the final tube that connects the urinary bladder to the outside through the penis, and allows urine to exit. The obstruction of the urethra can be complete or partial. 

Obstruction of the fetal lower urinary tract occurs in isolation in 1 in 3000 pregnancies. 

Why does it occur?

The cause of urinary obstruction is unknown and can occur in several forms, as a genetic syndrome or associated with other malformations. But in most cases it presents as an isolated disease with no other problems

Obstruction can occur for different reasons, but the most common is the existence of a membrane that obstructs the exit of the urethra, known as posterior urethral leaflets. Less frequently, in only 20% of cases, there is a severe narrowing of a path of the urethra (urethral stenosis), its final part (megalourethra) or even a total or partial absence of the urethra (urethral atresia). Finally, obstruction of the urethra may be due to a malformation at the entrance of the ureters to the bladder (ureterocele). 

What consequences does lower urinary tract obstruction have for fetal development?

If the obstruction is complete or very severe, the baby does not manage to urinate and the first effect will be on the bladder, which fills up as the kidneys continue to produce urine but cannot be emptied. This leads to an exaggerated growth of the bladder, which first struggles to overcome the obstruction by making its wall more muscular and thicker (bladder hypertrophy).

If the obstruction persists, the bladder will continue to grow, swelling in a balloon-like way, and may become so large that it occupies most of the fetal abdomen. This is called bladder distention and has two important consequences on the development of the fetus

  • There will be a decrease, or even absence, of the amniotic fluid that normally surrounds the fetus, a situation known as oligohydramnios. This occurs because the amniotic fluid is formed mainly from fetal urine and, when the fetus stops urinating, it disappears. Amniotic fluid is essential for the normal development of fetal lungs, and its absence produces an alteration in lung development, defined in its most severe degree as pulmonary hypoplasia, which are lungs of small size that cannot be used to breathe after birth. 
  • The distended bladder will produce a very significant increase in pressure due to the accumulation of urine that cannot be eliminated by the urethra as it normally would, so the pressure is transmitted upwards, dilating the tubes that connect the kidney with the bladder (the ureters). Finally, the pressure will also affect the kidneys, which can lead to kidney damage and affect their function. 

In the most severe cases, which are those in which the obstruction is severe or total and becomes evident already before 20-22 weeks of gestation, the baby will die after birth from pulmonary hypoplasia in more than 90% of cases.

If the baby survives he will have severe renal failure and, therefore, will need dialysis and to enter a kidney transplant programme in early childhood, usually already in the first year of life in more than 50% of cases. In some cases, the fetus can die even in utero, because the distended bladder causes great abdominal pressure and can alter heart function. 

Is it possible to avoid or reduce the risks of fetal lower urinary tract obstruction?

In many cases, if the obstruction is removed in fetal life, the serious problem of oligohydramnios can be solved, thereby reducing or eliminating the risk of pulmonary hypoplasia. In addition, this decompression relieves the pressure on the kidneys. 

Fetuses with urethral leaflet obstruction are normal fetuses in most cases, so if the only problem they have is this one, it makes sense to try fetal therapy to reverse the serious problem of urinary obstruction. The fundamental requirements for a fetus to benefit from fetal therapy are: 

  • It being a serious problem of obstruction: oligohydramnios exists already before 20 weeks of pregnancy. If the amount of amniotic fluid is normal there is no point in performing fetal therapy. 
  • It being an isolated problem: there are no other alterations, neither genetic nor in any other organ. 
  • Kidney function being preserved: Treatment will be done at a time when the kidneys are still functioning normally and it makes sense to try to prevent them from being irreparably damaged. Therefore, it is very important to evaluate renal function, which can be studied both in the urine and in fetal blood. 
What treatment options are there?

The main objective of the treatment is to enable the fetus to empty the bladder and thus normalize the amount of amniotic fluid, avoiding pulmonary hypoplasia and ensuring that the baby can survive after birth. Bladder decompression also helps improve kidney function, although it is not always fully achieved.

There are two types of fetal interventions to achieve these goals

  • Rupture (ablation) of the posterior urethra leaflets by fetal surgery (fetal cystoscopy). This is a treatment that is performed by fetal endoscopy. The introduction of a fine instrument (a tube 2–3 mm in diameter) into the bladder allows the visualization and breaking of the urethral leaflets, so that the urine is allowed to exit. 
  • Placement of a small tube that directly connects the bladder with the amniotic cavity (vesico-amniotic shunt) and allows the exit of urine through the abdomen. It is placed through the fetal abdominal wall by ultrasound control, and should remain until the end of gestation. 

Both interventions are performed with local anaesthesia and sedation of the pregnant woman, and with fetal anaesthesia. They are not very aggressive interventions for pregnant woman, but are of great technical difficulty

In our centre the first-line intervention is fetal cystoscopy. Although it is a much more difficult and sophisticated technique than the placement of a drain, it is also not very invasive for the pregnant woman and fetus. It allows, in case of success, a permanent solution in a single intervention and enables the fetus to urinate through the natural route. 

What appointments are needed for fetal surgery?

An in-patient admission of the pregnant woman will initially last 1–2 days and afterwards weekly check-ups with examination and ultrasound will be required, and she will have to maintain a low-activity lifestyle mainly at home until the end of pregnancy, especially for the first 3-4 weeks after the intervention. Normally, childbirth can be performed at term without any need to induce it prematurely. 

During pregnancy, you will receive the support of nurses specialized in fetal medicine, not only on a technical level but also on an emotional level throughout the process. In addition, we can put you in contact with other families who have gone through the same experience. This is very positive and helps to humanize and understand the problem in a much more intuitive way and without the difficulties that sometimes arise when receiving only technical information from professionals. 

Why BCNatal - Sant Joan de Déu?

This treatment is offered in a small number of hospitals in the world and none of them see a large number of cases. It is a complex, delicate and very high precision treatment. Given these difficulties, we are one of the most experienced centres in the world. As a pioneering development centre in fetal surgery, we continuously research and incorporate technologies that further improve accuracy, such as computer guidance techniques and robotic assistance. Through a pioneering system of 3D simulation of the obstruction we can visualize and print 3D models that allow us to simulate and practice the intervention before performing it, minimizing the necessary surgical time and the associated risks.  

For parents who wish to continue their pregnancy care and have their baby with us, we offer a fetal surgery team with the best survival and quality of life figures that can currently be obtained. Before surgery we evaluate each case in detail, performing very high-resolution ultrasound and magnetic resonance tests, and analyse them in multidisciplinary teams that include experts in each of the fields, including fetal medicine, fetal and paediatric surgery, neonatologists, radiologists and any other specialty that may be necessary.

We will discuss the case in detail with the parents and discuss the best options for the baby. Parents will be able to speak in detail not only with specialists in medicine and fetal surgery, but also with urologists and paediatric nephrologists who are experts in the monitoring and evolution of these children, to understand in detail the expected evolution in each case and the best options. 

To the excellence of the prenatal team is added a third-level paediatric centre as SJD Barcelona Children's Hospital, with teams formed by a large number of specialists with specific training in neonatal intensive care and who have the best and most modern technology.

Paediatric specialists, also part of the antenatal team, will continue to care for the baby once it is born and plan for possible interventions as necessary. The most common specialists are nephrologists and paediatric urologists. For surveillance during the first days after birth, the hospital has highly qualified medical and nursing professionals caring for these delicate patients 24 hours a day, 365 days a year. 

Once discharged, our paediatric teams will follow the baby for the first few years and take care of him or her to achieve optimal development and to solve any problems in this very fundamental part of life. 

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