Hydronephrosis

What is it?

Hydronephrosis is a condition in which urine accumulates in the kidney. Because of this, the kidney may enlarge. This condition can be mild, moderate, or severe and can involve:

  • blockage. Blockage can occur in the kidney or urethra, preventing normal urine flow.
  • vesicoureteral reflux (PDF) or uretero-pelvic junction obstruction).
  • a duplication anomaly involving more than one ureter leading from the kidney.
  • multi-cystic kidney

Often, the condition can be detected via ultrasound while the child is still in the womb. This is called antenatal hydronephrosis. Sometimes hydronephrosis is diagnosed after a child is born when the child develops a urinary tract infection.

What causes it?

In between the kidney and the bladder is a tube called a ureter. The most common cause of hydronephrosis is the narrowing of the ureter (called UPJ obstruction). If this occurs, it typically happens while the child is still in the womb and develops before the fourth month of pregnancy.

How is it treated?

During pregnancy, your physician also will carefully monitor how your child's kidney grows. If the hydronephrosis is discovered during pregnancy and is severe, an option may be for Children's team to perform the necessary surgery while your child is still in utero.

After birth, your physician will continue monitoring your child and may order tests such as an ultrasound (PDF), which helps assess kidney function, or a renal scan (which helps assess kidney function and drainage) or a VCUG (see VCUG for boys and VCUG for girls).

Treatment may include observation or surgery.

About surgery for hydronephrosis at Children's

The pediatric urology surgery team at Children's provides next-generation care to neonatal infants, newborns, children, and adolescents from throughout the Upper Midwest. The team consistently performs some of the most cutting-edge surgical procedures available, including newborn surgery, minimally invasive surgery, and robotic surgery, when appropriate. Urologic surgery is performed at Children's - Minneapolis, Children's - St. Paul and Children's West.

  • If you are a family member looking for a Children's specialist in urology surgery, please call the Center for Pediatric Urology at 1-800-992-6983.
  • If you are a health professional looking for a consultation or referral information, please call Children's Physician Access at 1-866-755-2121 (toll-free).

Return to Children's pediatric urology surgery home page.