Renal Agenesis

Renal agenesis is a congenital defect in which a baby is born without one or both kidneys.

The condition occurs when the kidney or kidneys fail to develop during fetal growth. The cause is unknown.

There are two types of renal agenesis:

• Unilateral renal agenesis – the absence of one kidney
• Bilateral renal agenesis – the absence of both kidneys

Unilateral Renal Agenesis

Unilateral renal agenesis, where the newborn is missing one kidney, occurs in an estimated 1 out of every 1,000 to 2,000 births. The defect is more common in pregnancies involving intrauterine growth restriction, where the fetus fails to grow at a normal rate, and in pregnancies with multiples (twins, triplets, etc.).

The prognosis for babies with unilateral renal agenesis is typically good. When one kidney fails to develop, the other kidney usually grows larger to compensate and do the work of two kidneys. In many cases the baby will have no symptoms.

Potential complications of unilateral renal agenesis include:

• Premature birth
• Vesicoureteral reflux, the backwards flow of urine from the bladder up into the ureters and sometimes the kidneys (ureters are the tubes connecting the bladder and kidneys)
• Later in life, hypertension, proteinuria (increased protein in the urine caused by kidney damage) and renal failure

In some cases unilateral renal agenesis may be associated with other abnormalities, including cardiac, female reproductive and gastrointestinal defects.

Bilateral Renal Agenesis

Bilateral renal agenesis, the absence of both kidneys, is rare, occurring in an estimated 1 out of every 4,000 to 5,000 newborns. The defect is more common in males. In some cases there is a family history.

Without kidneys the fetus is unable to produce urine. Fetal urine is the primary component of amniotic fluid in the second and third trimesters, cushioning the baby in the womb and enabling proper growth and development, including lung development. During pregnancy, the fetus continuously breathes in and swallows amniotic fluid, helping the fetal lungs expand.

Bilateral renal agenesis results in too little amniotic fluid, a condition known as oligohydramnios that can lead to severe complications, including:

• Underdeveloped lungs (pulmonary hypoplasia), leaving them too small to support the baby’s oxygen needs at birth
• Deformities of the limbs and face (known as Potter sequence) caused by compression in the womb
• Inability to grow to normal size, known as intrauterine growth restriction (IUGR)
• Preterm birth
• Labor complications, including umbilical cord compression, decreasing oxygen and blood flow to the baby
• Stillbirth
• Neonatal death

In addition to the absence of kidneys, babies with bilateral renal agenesis may have abnormalities involving other organs that failed to form.

The prognosis for babies born without both kidneys is poor. Newborns typically survive only a few hours or days due to underdeveloped lungs that lead to severe respiratory distress.

Diagnosis

Both types of renal agenesis may be diagnosed during a routine prenatal ultrasound.

Unilateral renal agenesis

Unilateral renal agenesis is usually detected based on the visualization of only one kidney. The single kidney may be larger than normal.

In cases where the condition isn’t diagnosed during pregnancy and the child has no symptoms, unilateral renal agenesis may go undetected until later in life when x-rays are performed, often for other purposes.

Bilateral renal agenesis

Bilateral renal agenesis is detected during pregnancy based on ultrasound findings that include:

• A severely low level of amniotic fluid
• Inability to visualize the kidneys, renal arteries, and bladder
• Other structural deformities

An MRI may be performed to confirm the diagnosis.

Specialized Evaluation and Prenatal Care

A diagnosis of renal agenesis during pregnancy enables your family and your healthcare team to plan ahead for the specialized treatment and expertise your baby may need during pregnancy or at birth.

If renal agenesis is diagnosed or suspected during pregnancy, you may be referred to a fetal center for further evaluation.

At Texas Children’s Fetal Center, we arrange for you to visit as quickly as possible for a comprehensive assessment by a team of specialists experienced in diagnosing and treating these congenital kidney conditions, including maternal-fetal medicine physicians (OB/GYNs specializing in high-risk pregnancies), fetal imaging experts, pediatric nephrologists, genetic counselors, and neonatologists. 

Additional testing may include:

• High-resolution anatomy ultrasound to confirm the diagnosis and look for other abnormalities
• Ultra-fast MRI for a more detailed view of fetal anatomy
• Fetal echocardiogram to evaluate the baby’s heart
• Amniocentesis and chromosomal analysis to identify any chromosomal anomalies

Following this thorough evaluation, our specialists will meet with you about the results, discuss your baby’s prognosis, and answer any questions your family has to help you make the most informed decisions regarding your child’s care and treatment.

Treatment During Pregnancy

Mother and baby will be closely monitored throughout pregnancy with more frequent ultrasounds to assess fetal growth and the amniotic fluid level.

In cases of bilateral renal agenesis, a condition that is incompatible with postnatal life, a specialized service of palliative care is available to offer comfort care for the neonate after birth.

Delivery

Delivery and postnatal care should be carefully planned and coordinated with a team of fetal and pediatric specialists experienced in renal agenesis.

Our Fetal Center team works closely with specialists from Texas Children’s Renal Service, one of the largest programs in the world for the treatment of children with congenital and acquired kidney diseases. Here, the pediatric specialists treating your newborn have been an integral part of their care team since before birth.

Treatment After Birth

Unilateral renal agenesis

For children with unilateral renal agenesis, treatment needs will depend on the health of the remaining kidney, any symptoms the baby has, and the presence of any associated abnormalities.

All babies born with this condition require ongoing monitoring by a nephrologist experienced in renal agenesis, with annual blood pressure, urine and blood testing to evaluate kidney function.

For females, a pelvic ultrasound may be performed after birth to look for any associated abnormalities in the reproductive tract.

Children born with one kidney may be advised to avoid contact sports or use protective gear to prevent injury to the remaining kidney.

Bilateral renal agenesis

Newborns with bilateral renal agenesis rarely survive more than a few hours or days after birth due to severe pulmonary hypoplasia, where the lungs are too underdeveloped to support the body’s oxygen needs.

Postnatal Care Team

Depending on the type of renal agenesis and your baby’s symptoms, his or her postnatal care team may include:

• Neonatologist
• Pediatric nephrologist

Patient Support Services

Emotional support is vital for families facing a diagnosis of bilateral renal agenesis.

We offer our Fetal Center patients:

• Family centered palliative care
• Women’s mental health services for reproductive loss and grief
• Referrals to local and national support groups as well as other families who have had similar experiences

Why Texas Children’s Fetal Center?

• A single location for expert maternal, fetal and pediatric care. At Texas Children’s Hospital, mother and baby receive the specialized care required for the diagnosis and treatment of renal agenesis all in one location, for highly coordinated care and treatment planning.
• A skilled, experienced team with proven outcomes. We have a dedicated team of maternal-fetal medicine specialists, fetal imaging experts, pediatric nephrologists, genetic counselors, neonatologists and others who work in concert to care for you and your baby every step of the way, using proven protocols we’ve developed over the years. With their combined expertise and unified approach, this team offers the best possible care for pregnancies involving renal agenesis.
• We care for children’s needs at every stage of life. Our comprehensive approach starts with your first prenatal visit and continues through delivery, postnatal care, and childhood, thanks to one of the nation’s leading teams of fetal and pediatrics specialists for the care and treatment of rare congenital conditions.

Videos

• Texas Children’s Fetal Center: Our care began before he/she was born

Additional Resources

• 6 things to consider when choosing a fetal center