Neonatal Hydronephrosis (Patient Information)

Neonatal hydronephrosis is a condition affecting the kidneys in newborns. This occurs when the baby's urine does not drain properly into the bladder. When this happens, the urine gets trapped and overfills the kidneys. The collecting part of the kidneys begins to stretch and enlarge (get bigger). This then leads to pain, bleeding, or frequent infections, which may further damage your baby's kidneys. Mild neonatal hydronephrosis may resolve before your baby reaches the age of one year.

The urinary system is made up of the kidneys, ureters, bladder, and urethra. The kidneys are two bean-shaped organs and are in the back of the abdomen (belly) on both sides of the spine. These filter the blood to remove waste products and form urine. The urine flows from the kidneys down through the tubes called ureters. From the ureters, the urine goes down and is stored for a short time in the bladder. The urine passes out of the body through another tube, called the urethra, when you urinate. With proper treatment and follow-up, your baby's symptoms may be relieved and his quality of life may be improved.

What causes neonatal hydronephrosis?

The following are possible causes of neonatal hydronephrosis:

  • Obstruction: A blockage of urine flow which can occur somewhere along the urinary tract may cause hydronephrosis. The blockage is usually a narrowing or kinking of the ureters.
  • Reflux: This happens when urine travels back up to the kidney. This often occurs when the muscles at the junction of the ureter and bladder do not work properly.
  • Others causes: These may include having fluid-filled cysts in the kidneys. Problems since birth may cause neonatal hydronephrosis. These may include problems such as having two ureters from one kidney or ureters draining outside the bladder.

What are the signs and symptoms of neonatal hydronephrosis?

Neonatal hydronephrosis does not usually cause any signs and symptoms. If symptoms are present, your baby may have trouble passing urine. His urine may be cloudy or pinkish to reddish in color. He may have a fever or abdominal (belly) pain.
How is neonatal hydronephrosis diagnosed?

Your baby may need any of the following tests:
Before your baby is born:

  • Fetal ultrasound: Caregivers may diagnose neonatal hydronephrosis while your baby is inside your womb by doing a fetal ultrasound. This test uses sound waves to show pictures of your baby that will show on a TV-like screen. Caregivers will learn the size and shape of his kidneys, and look for a mass, stones, or cysts. They may also know if there are other obstructions or problems with the amniotic fluid (fluid around baby).
  • Urine tests: This test checks how well your baby's urinary tract is working. Caregivers will take a urine sample from your baby's urinary bladder. The sample will then be sent to the lab for tests.

After your baby is born:

  • Intravenous pyelogram: This is also called an IVP. An IVP is an x-ray of the kidneys, bladder, and ureters. The IVP shows how well your baby's kidneys drain urine. Dye is put into his vein (IV) which makes these organs show up better in x-ray pictures. He may need to have more than one x-ray over short periods of time during his IVP.
  • Kidney scan: During this test, pictures are taken of your baby's kidneys. Your baby is given a small, safe amount of dye in an IV. Caregivers can look at the pictures to know how well his kidneys are working. This may also tell the cause of any blockage in his urinary tract and how bad it is.
  • Magnetic resonance imaging: This test is also called an MRI. An MRI uses magnetic waves to take pictures of your child's abdomen. During an MRI, pictures are taken of his urinary tract, muscles, or blood vessels. He will need to lie still during an MRI. Never enter the MRI room with an oxygen tank, watch, or any other metal objects. This may cause serious injury.
  • Renal ultrasound: This is a test using sound waves to look at your baby's kidneys. Pictures of his kidneys show up on a TV-like screen.
  • Voiding cystourethrogram: This test is also called a VCUG. It is a special x-ray that checks your baby's urinary tract. A catheter (tube) is placed in the urethra. The bladder is then filled with a liquid dye. X-ray images will be taken as the bladder fills and empties. The images will show if there is any back flow of urine into the ureters and kidneys and how well the bladder empties. It is also used to know if there is a blockage in the urethra.

How is neonatal hydronephrosis treated?

Treatment for neonatal hydronephrosis aims to restore normal urine flow, relieve symptoms, and prevent serious problems. This is done by treating the cause and controlling the extent of damage. A catheter may be placed right after he is born to help drain his urine. Sometimes, caregivers may do surgery to remove blockage so urine can drain to the bladder. A shunt may also be placed to help widen a narrowed part of your baby's urinary tract. Antibiotic medicines may be given to help your child fight an infection caused by a germ called bacteria. Neonatal hydronephrosis may be cured with proper and timely treatment.

Where can I get support and more information?

Accepting that your baby has neonatal hydronephrosis may be hard. You, your family, and those close to you may feel scared, sad, or angry. These are normal feelings. Talk to your baby's caregivers, your family, or friends about your feelings. You may also want to join a support group. This is a group of people whose children also have neonatal hydronephrosis or other kidney diseases. Ask your caregiver for the names and numbers of support groups near you. You may also want to contact the following for more information:

  • American Association of Kidney Patients
  • 3505 E. Frontage Rd, Suite 315
  • Tampa, FL33607-1796
  • Phone: 1-800-749-2257
  • Web Address:

  • National Kidney Foundation
  • 30 East 33rd Street
  • New York, NY 10016
  • Phone: 1-212-889-2210
  • Phone: 1-800-622-9010
  • Web Address: