Lower Urinary Tract Obstruction (LUTO), also known as obstructive uropathy, is a rare birth defect caused by partial or complete blockage of the tube that connects the bladder to the penis, where urine is released (the urethra). This defect affects male fetuses while they are still in the womb. While in the womb, fetal urine is an important component of amniotic fluid that surrounds the fetus and is important for normal fetal lung development. If the urethra is completely blocked, the fetal bladder can become enlarged and amniotic fluid levels can decrease. This can lead to underdevelopment of the lungs, which can be life-threatening at birth. Lack of amniotic fluid can also cause less protection for the fetus. Doctors often diagnose this birth defect early through frequent observation of the fetus using ultrasound. Doctors may recommend fetal shunting, where a hollow tube is inserted through the fetal abdominal wall to the bladder to allow fetal urine to be released into the surrounding amniotic fluid. Once the baby is delivered, doctors may also suggest surgery be performed on the infant to remove the urethra blockage.