Open Accessibility Menu


Hydronephrosis, while not a specific disease, is a radiographic finding that shows that urine is filling the kidney more than normally seen, and is commonly found on an ultrasound. Hydronephrosis may be unilateral (affecting just one kidney) or bilateral (affecting both kidneys). In children with mild hydronephrosis, the condition often resolves on its own. This is a relatively common congenital condition (a condition a baby is born with) that occurs in both boys and girls.

Causes of Hydronephrosis

Hydronephrosis is not a disease but may be caused by an underlying condition including:

  • A partial obstruction, which is a blockage that prevents the urine from draining completely out of the kidney.
  • Reflux, where urine comes back up the ureter into the kidney (think of acid reflux). Reflux of urine back into the kidney(s) can occur for a variety of reasons and needs an evaluation to determine the cause.

Diagnosing Hydronephrosis

Thanks to advances in imaging technology, diagnosis of certain urologic conditions such as hydronephrosis can begin in the womb either through routine or specially-ordered ultrasound exams on the expecting mother, typically around the fourth month of pregnancy or later. Dr. Adam Kern can consult on conditions diagnosed on screening sonogram examinations during pregnancy such as hydronephrosis and other kidney concerns.

If hydronephrosis is suspected in a prenatal ultrasound, the condition of the baby’s kidneys will be monitored throughout the remainder of your pregnancy. Upon delivery of your baby, Dr. Kern can further evaluate the condition.

Your doctor may order imaging tests such as:

  • A renal ultrasound, which provides a clear picture of the extent of the hydronephrosis.
  • A voiding cystourethrogram (VCUG), a special X-ray that can show reflux or if there is a urethral obstruction, two common causes of hydronephrosis.
  • A MAG3 scan, which is a type of study that can measure both kidney function and drainage, important in diagnosing obstruction.

While most children experience few or no symptoms, children with more severe hydronephrosis may experience one or more of the following symptoms:

  • Discomfort in the side or flank
  • Abdominal pain or discomfort
  • Hematuria, or blood in the urine
  • Urinary tract infections

The Good News

Most babies and young children with hydronephrosis may have few or no symptoms. In mild and even moderate cases, hydronephrosis often resolves on its own with no intervention necessary and no further issues down the road.

Treating Hydronephrosis

Upon learning more about your child’s hydronephrosis and its cause, your pediatric urologist will go over the results of the diagnostic tests and develop a treatment plan that meets your child’s specific needs. Our pediatric specialists understand that any time there is a health issue with a child, it can be a very stressful and scary time for the parents.

That is why we will walk you through every step and involve you in every decision about your child’s treatment and health care which may include:

  • Observation. In most cases, your doctor will observe the child’s kidney over time, performing renal ultrasounds periodically. Most cases of hydronephrosis clear up on their own.
  • Surgery. In rare cases, your pediatric urologist may recommend surgery to correct the cause of your child’s hydronephrosis, especially if the condition is affecting the function of the kidney. A common surgical procedure for obstructive hydronephrosis is pyeloplasty which is used to repair an obstruction in the drainage portion of the kidney. Children often stay in the hospital and the procedure has a very high success rate.