Lower Urinary Tract Obstruction (LUTO)
or Bladder Outlet Obstruction (BOO)
Normal Anatomy
The urinary tract is made up of organs that produce and store urine, or pee. It includes:
- Two kidneys
- Two ureters
- The bladder
- And the urethra.
The kidneys make the urine, which flows through the ureters into the bladder, where it is stored. When the bladder is full, it pushes the urine out through the urethra.
The kidneys and ureters are called the upper urinary tract and the bladder and urethra the lower urinary tract.
In the uterus, or womb, the urine is called amniotic fluid, and it cushions the fetus.
Lower Urinary Tract Obstruction (LUTO)
What happened?
LUTO happens when the urethra is blocked, and urine can’t flow out of the body. This causes urine to build up in the kidneys and ureters. Over time, this can harm the kidneys.
Other Effects
When urine can’t leave the body, the amniotic fluid decreases. Amniotic fluid helps the fetal lungs develop. Without enough fluid, the fetal lungs may not grow properly.
While the fetus is in the womb, the placenta acts as both lungs and kidneys. But after birth, the baby can’t rely on the placenta anymore, and the lungs and kidneys must begin functioning on their own.
If LUTO has caused damage to the baby’s organs, they may not work properly which can affect the baby’s health and lower the chance of survival.
Causes of LUTO
LUTO can happen because of a problem the baby’s genes, or it can happen for no known reason (“isolated” LUTO). Whether genetic or isolated, LUTO is caused by a structural issue with the urethra. After birth, doctors can run tests to find out exactly why LUTO happened, which helps them decide how to treat the baby.
The most common structure anomalies are:
Posterior Urethral Valve
Complete Obstruction
This is where a fold of tissue blocks the urethra, stopping urine from leaving the body.
Urethral Atresia
Complete Obstruction
This is where the urethra is absent, stopping the flow of urine.
Urethral Stricture
Partial Obstruction
This is where parts of the urethra are narrowed, restricting the flow of urine.
How LUTO is Diagnosed
Doctors use several tests to find out if a fetus has LUTO. These tests include:
Ultrasound
This test uses sound waves to make pictures of the fetus inside of the womb. It helps doctors check the baby’s organs, to look for any problems, and monitor growth.
MRI
This test makes images of the fetal body strong magnets. MRI helps doctors look closely at certain areas, like the fetal urinary tract.
Fetal Echocardiography
This test looks at the fetal heart to check for any malformations, as babies with birth defects such as LUTO are at higher risk for heart issues.
Amniocentesis
In this test, doctors take a small sample the amniotic fluid surrounding the baby. They can check the cells in this fluid for genetic problems or conditions.
Fetal Urinary Electrolytes
This test checks how well the baby’s kidneys are working by draining urine from the bladder to test it.
Impact on Development
When the urethra is blocked, the baby can’t urinate, which affects other parts of the body.
Kidneys
When urine builds up, it can damage the kidneys.
This can cause hydronephrosis, or very swollen kidneys, which can lead to kidney failure .
It can also cause multicystic dysplastic kidneys, which means the kidneys don’t grow properly and are filled with fluid instead of normal kidney tissue.
Lungs
Normally, the baby “breathes” in amniotic fluid, which helps the lungs grow, like filling a water balloon. But when the baby can’t release urine, there isn’t enough amniotic fluid to help the lungs grow.
This may lead to hypoplastic lungs, meaning the lungs are undeveloped and can’t work properly after birth .
Physical Issues
Amniotic fluid cushions the fetus in the womb, giving it space to move around. Without enough fluid, there is less room for the fetus, which can cause problems like facial deformities (“Potter facies“), short limbs, clubbed feet, and joint contractions (where the joints can’t move properly).
These physical defects are knowns as Potter syndrome.
The outlook for babies with LUTO depends on how serious the blockage is and how badly other organs, like the kidneys or lungs, are affected.
Some babies may need treatments like a ventilator, dialysis, or even a kidney transplant after birth. Babies with severe LUTO have a lower chance of surviving, and even if they do survive birth, they may still need a lot of medical support.
Intervention Options
There are interventions that can help some babies with LUTO, but they don’t fix everything, and the baby will likely still have kidney or lung damage. Doctors use many tests to decide if these interventions will help.
Vesicocentesis
This is a temporary measure where a needle is used to take urine out of the baby’s bladder. This helps relieve pressure and reduce damage to the kidneys. This may need to be repeated several times throughout the pregnancy.
Pigtail Shunt
A shunt is a small tube that is put into the baby’s bladder through the womb. The tube helps the fluid drain into the amniotic space, which can reduce the build-up of urine and help the baby’s kidneys. This is a temporary measure until the baby is born.
Amnioinfusion
In this procedure, a needle is used to put amniotic fluid into the uterus to help cushion the fetus and help the lungs to grow better. This may need to be repeated several times throughout the pregnancy.
Fetal Cystoscopy
In rare cases, doctors can perform a small surgery on the fetus using a cystoscope (small, surgical camera) to remove the blockage in the fetal urethra.
About my Thesis:
Accessible Education for LUTO Patients: A Study of Multimodal Tools to Support Literacy and Emotional Wellbeing
Year
2025
Thesis Committee
Michelle Kush, MD
Thesis Preceptor
Jennifer Fairman, CMI
Thesis Advisor
Format
3D Animation, Website
Objectives:
with foundational knowledge.
Facilitate communication by developing online materials that empower patients to explain their condition to family and friends, reducing the need for repeated explanations.
Support patient education by providing educational materials to healthcare providers.
Tools
ZBrush, Cinema4D, RedShift, AfterEffects, Illustrator, Photoshop