Overview

Hydronephrosis is swelling of one or both kidneys. Kidney swelling happens when urine can't drain from a kidney and builds up in the kidney as a result. This can occur from a blockage in the tubes that drain urine from the kidneys (ureters) or from an anatomical defect that doesn't allow urine to drain properly.

Hydronephrosis can happen at any age. Hydronephrosis in children may be diagnosed during infancy or sometimes during a prenatal ultrasound before the baby is born.

Hydronephrosis doesn't always cause symptoms. When they occur, signs and symptoms of hydronephrosis might include:

• Pain in the side and back that may travel to the lower abdomen or groin
• Urinary problems, such as pain with urination or feeling an urgent or frequent need to urinate
• Nausea and vomiting
• Fever
• Failure to thrive, in infants