Foetal Lower Urinary Tract Obstruction (LUTO) - Causes, Diagnosis And Treatment

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During the development of the foetus inside the womb, each and every organ system develops at its own pace. Most of the organ systems of the foetus are already completely functioning even before their birth, the major system being the excretory system. The urinary bladder, kidneys and the urinary tract of a foetus begin functioning around 4-5 months after gestation and begin filtering the amniotic fluid gulped down by the foetus. But sometimes an abnormality in the urinary tract can obstruct the flow of urine. Known as foetal lower urinary tract obstruction, this foetal condition is extremely rare and complicated.

Read on to find out everything about foetal lower urinary tract obstruction - its causes and effects on the foetus.

What Is Foetal Lower Urinary Tract Obstruction?

The human urinary system consists of two kidneys, two ureters, a urinary bladder and the urethra. The urine which is formed in the kidneys passes onto the urinary bladder with the help of the ureters. The urine then passes out of the body by the urethra.

During the foetal development of these organs, an anomaly in any part of the system can result in the failure of the urine to pass out of the body. This condition is called foetal lower urinary tract obstruction.

If the foetus is unable to pass urine, this can result in a chain of other events. For starters, the level of the amniotic fluid in the womb decreases. This has a direct effect on the development of the lungs as they do not grow in the absence of adequate amniotic fluid.

Also, the obstruction can cause high pressure on the kidneys, which can lead to their enlargement and eventually damage them.

What Causes Foetal Lower Urinary Tract Obstruction?

Foetal lower urinary tract obstruction can be caused due to a variety of reasons. The urine may be difficult to pass due to a narrow urethra, or a flap obstructing the path. This may lead to pressure on the kidney, which may cause it to swell.

Foetal lower urinary tract obstruction is commonly found in male foetuses. It is known to be genetic and caused due to a chromosome abnormality.

How Is Foetal Lower Urinary Tract Obstruction Diagnosed?

The condition is very clearly detected with an ultrasound scan due to the presence of swollen kidneys. Also, there may be various levels of urinary tract obstruction depending on where the obstruction is present in the urinary tract.

To confirm the degree and make an exact diagnosis, doctors may recommend the following tests and scans.

- Ultra fast foetal MRI - This is used to determine the genitourinary tract of the foetus.
- Serial renal function profile - a small amount of foetal urine is extracted from the kidneys and studied.
- Foetal chromosome studies - This helps study the defective gene in the foetus's gene pool to determine if it is hereditary.

In addition to the above tests, a detailed ultrasound scan can help determine the presence of cysts in the kidneys.

What Are The Complications Of Foetal Lower Urinary Tract Obstruction?

The complications of the condition usually depend on the type and kind of obstruction in the urinary tract. However, the major complications of the condition arise due to insufficient amniotic fluid.

The kidneys of a foetus start functioning by 14-15 weeks after gestation. At around this time, there is very little amniotic fluid in the sac. The foetus constantly gulps down this liquid which is processed by the kidneys. It then expels the urine back into the amniotic sac to form the amniotic fluid.

Any kind of obstruction in the urinary system of the foetus, thereby, results in less amount of amniotic fluid. This causes another set of complications that include underdevelopment of lungs. Also, less amount of amniotic fluid causes deformations of the facial structure of the foetus due to the absence of a cushion against the uterine walls.

Another life-threatening complication due to foetal lower urinary tract obstruction is the underdevelopment of the lungs, which may cause a serious complication during childbirth.

How Is Foetal Lower Urinary Tract Obstruction Treated?

Depending on the type and degree of foetal lower urinary tract obstruction, the treatment may vary.

Due to the fact that it involves an undelivered foetus, the procedure cannot be too invasive. The method of placing a shunt in the baby's bladder into the amniotic sac can help relieve the urine and prevent further damage to the kidneys. The final treatment can be performed after birth. However, it is important for the baby to be continuously monitored.

The success of the surgery, however, depends on the damage of the kidneys. If the kidneys haven't been damaged, babies go on to live a healthy life after the surgery to remove the obstruction. If the kidneys are beyond damage, they may need a dialysis or a kidney transplant.