We offer pediatric urology care from prenatal development through age 18. The expert urologists at the University of Chicago Medicine Comer Children's Hospital provide care to children with conditions affecting the kidneys, ureter, bladder, urethra, penis and testicles.

Hydronephrosis results from dilation or stretching of the inside of the kidney. This part of the kidney is called the "collecting system" because the urine made in the solid outer part of the kidney collects in the funnel-shaped kidney pelvis and then drains down the ureters to the bladder.

Normally, the urine drains so well from the kidney to the bladder that no urine is visible in the kidney on ultrasound studies. Hydronephrosis is the term used to describe the extra urine seen in the kidney. Sometimes, the urine dilates both the kidney and the ureter resulting in a condition called hydroureternephrosis.

Hydronephrosis has not been linked to anything parents may have done during pregnancy, but it can be hereditary. Usually, these abnormalities are seen during the mother's prenatal ultrasound evaluation. In some cases, however, hydronephrosis may not be recognized until after birth or later in childhood.


We know that there are several causes of hydronephrosis. Often, it results from a narrowing at the point where the ureter leaves the kidney. This condition is called ureteropelvic junction obstruction (UPJ obstruction). The hydronephrosis depends on the extent of the blockage and the amount of stretching of the kidney. Hydronephrosis ranges from mild to moderate to severe. The cause of this narrowing is not currently known but probably develops before the fourth month of pregnancy.

A second cause of hydronephrosis is reflux or the backward flow of urine from the bladder back up into the ureters and kidneys. This condition may be hereditary and is a common cause of serious urinary tract infections in children.

Blockage at the lower end of the ureter is another cause of hydronephrosis and hydroureter. The ureter may enter the bladder in an abnormal area or may be covered with a thin membrane that prevents the drainage of urine into the bladder. The exact cause of the obstruction may not be known until special tests are performed.

What should I expect if my newborn has hydronephrosis?

Your child's pediatrician will need to be told that your baby was diagnosed with hydronephrosis before birth. In the first days of life, your baby’s urinary tract will be studied with an ultrasound to look more carefully at the kidneys and bladder.

After this is done, your child's pediatrician will ask a pediatric urologist to evaluate your baby. This consultation may happen before your baby goes home from the hospital or one to two weeks later in the Comer Children's pediatric urology clinic. Your baby will need to take a low dose of antibiotic once a day to prevent infection until the exact cause of the hydronephrosis is known.

In the first two weeks of life, your baby will undergo a special bladder X-ray called a voiding cystourethrogram (if needed). During this study, a small tube is placed into the bladder through the urethra. Our pediatric radiologist will fill the bladder with a special dye and watch as your baby urinates. If your baby has reflux, the radiologist will see the urine go backwards from the bladder to the kidneys as the bladder fills or as the baby urinates. At the end of the study, the bladder tube will be removed and your baby will urinate out the remaining dye.

Some babies will need an additional test called a kidney or renal scan to determine how well the kidney drains and how well it functions. This will be done when the baby is 6 to 8 weeks old. If the drainage from the kidney is slow because of UPJ obstruction, your baby will require careful follow up with additional ultrasounds every two months in the first year of his or her life.


At Comer Children’s, the pediatric urologist will examine all options before performing surgery for hydronephrosis. In children with mild hydronephrosis or reflux, it is safe to carefully monitor these children. This is called observational therapy. Observational therapy involves closely watching your child's health and kidney growth while your child takes low dose antibiotics to prevent infection. Typically, the problems correct themselves as the child grows.

Some conditions causing hydronephrosis will need to be corrected with surgery. In some cases, the pediatric urologist will operate through a small telescope placed into your baby’s bladder while the baby is still very young. Early relief of an obstruction in the bladder or ureter will allow your baby’s urinary tract to heal and develop normally.

Children with VUR have an abnormal urine flow. Normally, urine flows down from the kidneys through tubes called ureters into the bladder. In VUR, the urine can back up from the bladder into the ureters and kidneys.

Sometimes, VUR is caused by a birth defect — specifically, a leaky valve between the ureter and bladder. As a child gets older, the valve may begin to work normally, so VUR may disappear. But sometimes it doesn't. In other children, VUR may be caused by something that blocks the urine flow from the bladder. For example, a child’s habit of "holding in" the urine can sometimes cause VUR. VUR tends to run in families and most often affects girls.


Typically, a urinary tract infection is the most common sign of VUR in infants and young children. VUR can lead to infection because bacteria can build up in the urine that doesn't empty from the bladder. This infection can then move up into the kidneys. Older children may have other symptoms, such as bedwetting and high blood pressure.


Imaging tests can help doctors determine if there is a problem with the urinary tract. Some of these tests include:

  • Ultrasound, which uses sound waves to check the kidney and bladder
  • Voiding cystourethrogram (VCUG), which is a special bladder X-ray that checks the flow of urine. This test is conducted by a pediatric radiologist, who will insert a small tube into the urethra and fill your child's bladder with a special dye. If your child has VUR, the radiologist will see the dye flow backwards up toward the kidneys as the bladder fills or as your child urinates.

These tests can help doctors determine the severity of VUR, which is rated from grade I (very mild) to grade V (very severe).


Without medical attention, VUR can cause infections that move into the kidneys and cause scars. This can permanently damage the kidneys. Fortunately, there are medical and surgical approaches to treating VUR that can help prevent this.

At Comer Children's, children receive comprehensive treatment for VUR from our highly trained pediatric urologist. Some children may only need conservative management. They will require a daily low-dose of antibiotics until they are age 3 to 5 years. This will help prevent urinary tract infections. They'll also need regular imaging tests. If children have started or finished potty training, they will also take part in bladder retraining. Comer Children's is home to a well-respected bladder clinic, where children undergo a customized program that helps them learn dietary changes and new behaviors to prevent infections. Under the guidance of a nurse practitioner, children learn how to empty their bladder on a schedule and avoid holding their urine.

When conservative treatment fails or is not the preferred option, children have access to the latest surgical therapies available at Comer Children's. This includes a minimally invasive approach to VUR. During this outpatient procedure, the child receives general anesthesia. Then, our pediatric urologist places a small tube through the urethra and into the bladder. The doctor injects a safe, nontoxic gel into the bladder wall, near where the ureters join the bladder. This gel forms a bulge that helps prevent urine from flowing back up into the ureter. Research shows that this treatment has a 70 to 80 percent cure rate with one injection and this could be safely repeated, if needed, to reach a 100 percent cure rate.

Robotic surgery is an option for all grades of VUR, but endoscopic correction is still the best for low grades I-III and it has a role in high grade (IV-V) VUR treatment instead of open surgery. The advantages of the robotic approach are the avoidance of large surgical scars, minimal pain and a faster recovery. The success rate is almost equal to open surgery — 95 percent.

Traditional, or open surgery, is another approach, but typically only for higher grades IV or V. This type of surgery has a higher success rate than the minimally invasive approach. However, it is more invasive. The doctor will make an incision in the lower abdomen and move the ureter to a different angle so that urine will not back up from the bladder.

Some of the most common pediatric urological problems — anomalies in the kidney (UPJ, duplex kidney) and bladder (VUR, neurogenic bladder) — occur during fetal development. Sometimes these conditions require surgical reconstruction. Mohan Gundeti, MD, is an expert in kidney reconstruction (pyeloplasty) and bladder reconstruction (cystoplasty). In most cases, these reconstructions can be done using minimally invasive procedures, including robot-assisted techniques. Some genital and bladder abnormalities like hypospadias and cloaca bladder exstrophy require open reconstruction. Others, like undescended testis, can usually be corrected laparoscopically. In addition, a multidisciplinary team offers surgical care and long-term management for children born with complex anorectal malformations.

The clinic for fetal urological diseases focuses on diagnosis and intervention for various urological anomalies (i.e. hydronephrosis, posterior urethral valve) discovered before a baby is born. The clinic offers diagnosis, treatment and counseling for women with high-risk pregnancies related to bladder and genital abnormalities.

The clinic for neurogenic bladder disorders concentrates on neurogenic bladder, a condition sometimes seen in children with spina bifida. The urologist works with a team of neurosurgeons and orthopaedic surgeons to evaluate and manage this complex condition. If reconstruction of the bladder is necessary, the procedure is usually performed with the da Vinci robotic surgical system.

If a child is experiencing an interrupted or intermittent flow of urine, he or she may have a voiding dysfunction. Sometimes this is the result of a neurological problem, but is more commonly caused by a child’s habit of "holding in" the urine. The voiding dysfunction clinic at Comer Children’s, under the direction of a pediatric urologist and a dedicated nurse specialist, offers comprehensive evaluation of voiding dysfunction using state-of-the-art equipment and treatments, such as urodynamics and biofeedback. In rare cases when surgery is required, minimally invasive techniques including robotic surgery are used.