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



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

  • A partial obstruction - a blockage is preventing 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. 



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. Robert Mevorach 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. Mevorach can further evaluate the condition. Your doctor may order imaging tests such as:

  • A renal ultrasound - 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


If the condition is not seen on a prenatal ultrasound, it's important to note that most babies and young children with the condition may have few or no symptoms. In mild and even moderate cases, the issue often resolves on its own with no intervention necessary. 

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


Learn More About Hydronephrosis Treatment Here.