Lower Urinary Tract Obstruction (LUTO)

Lower Urinary Tract Obstruction (LUTO) refers to a group of birth abnormalities where a fetus’ lower urinary tract is blocked, preventing urine from leaving the bladder. This blockage can cause damage to the developing kidneys due to “backward” pressure above the obstruction. It commonly also results in low amniotic fluid levels around the pregnancy, which can poorly impact fetal lung development. LUTO requires close monitoring as a pregnancy proceeds. It can require in-utero treatments to relieve the increased pressure in the urinary system, or lead to neonatal interventions, even kidney transplant, after birth.

The lower urinary tract can be thought of as a pipe that carries urine from the bladder out through the urethra. LUTO is a collective term referring to any type of blockage in the lower urinary tract. Medical conditions classified under LUTO may include posterior urethral valve, urethral atresia, anterior urethral valves, prolapsed ureteroceles, and other diagnoses.

LUTO is often diagnosed during a routine prenatal ultrasound in an otherwise uncomplicated pregnancy; in severe cases it can be identified as early as 11-14 weeks. Once LUTO is diagnosed, a comprehensive fetal anatomic survey is also performed, since urinary abnormalities can occur in conjunction with other structural defects, and fetal genetic testing will also commonly be offered, since fetal birth defects can be associated with a variety of genetic syndromes. In some cases, further testing of fetal urine or blood may be recommended to evaluate fetal kidney function and given more information about long-term outcomes for the newborn.

LUTO is reported in about 1 in 5,000 live births. Although this condition is rare, our team of specialists at UCLA has extensive experience caring for families with a child affected by this condition.

Most LUTO cases are isolated, however, in about 10% of affected pregnancies there may be an associated genetic condition. Genetic counseling and testing are offered to families with this diagnosis at UCLA.

Amniotic fluid is largely composed of fetal urine in the second and third trimester. In LUTO, the fetus cannot empty the bladder to allow urine to drain into the amniotic sac. The bladder becomes large and overdistended. The blocked urine from the kidneys results in increased pressure from the urine backing up into the drainage system inside the kidneys, which can lead to kidney damage. The obstruction can lead to lifelong changes of both the bladder and the kidney. At the same time, the blockage may result in decreased amniotic fluid around the fetus which can cause underdevelopment of the fetal lungs (pulmonary hypoplasia).

Serial evaluation via ultrasound to assess the ongoing development and function of the kidneys is a key component of assessing fetal well-being during the pregnancy.

In select cases, fetal intervention, such as placement of a thin drainage tube (a “shunt”) from the bladder into the amniotic cavity to bypass the blockage, may be recommended. Our team of specialists at UCLA Health will provide close monitoring during pregnancy and help to coordinate the surgical care your baby may need after delivery.

Once a diagnosis of LUTO is made, your care team will meet with you to talk about your baby’s condition, the management for the remainder of your pregnancy, and your delivery options. You may have more frequent ultrasounds during the remaining weeks of your pregnancy to monitor your baby’s health before delivery. Please know that at UCLA Health, we have experts to care for both you and your baby during pregnancy and after delivery, with a team that includes high-risk obstetrics, neonatology and pediatric urology. Your team will also include additional specialists such as lactation and child life specialists to ensure a holistic, person-centered experience.

After your delivery, your baby may be transferred to the neonatal intensive care unit (NICU) where specialized doctors and nurses will provide care for your baby. A pediatric urologist will examine your baby to determine what type of procedure is needed.

How your child’s LUTO is treated depends on several factors, including the newborn’s gestational age at delivery, their level of respiratory development, what caused the LUTO, and how the urinary system was affected, and if other birth defects or genetic problems may be present.

You and your baby will be cared for by expert specialists in maternal-fetal medicine, pediatric urology, clinical genetics, nursing, lactation specialists, social workers, mental health specialists, child life specialists and neonatologists and the neonatal intensive care unit (NICU).

Your UCLA Health care team will support the options you have in your health care. When a pregnancy is diagnosed with fetal LUTO, you will not necessarily require a cesarean birth, and a vaginal delivery may still be possible. Depending on your unique situation, your care team will discuss whether you can deliver your baby vaginally or if a cesarean section will be required.

The probability of a LUTO happening with your next pregnancy depends on whether there is an underlying genetic cause. A genetic counselor will help decide if genetic testing for you and your partner is recommended before a future pregnancy, based on your specific history and results.