Hydronephrosis occurs when urine builds up in the kidneys and cannot drain out to the bladder. This causes one or both kidneys to swell.

Two urinary system problems cause hydronephrosis:

  • A blockage may prevent urine from draining out of the kidneys.
  • A condition known as reflux may cause urine to flow back into the kidneys from the bladder.

These problems may in turn result from:

  • A congenital blockage or defect in the urinary system
  • Kidney stones
  • A blood clot
  • Scarring of the ureters
  • A tumor in the bladder, cervix, colon or prostate
  • Enlarged prostate
  • Enlarged uterus during pregnancy
  • Persistent urinary infection in the kidneys
  • Neurogenic bladder
  • Injury to structures in the urinary system, from surgery or trauma

Treatment for Hydronephrosis

Treatment involves:

  • Draining excess urine from the kidney
  • Removing the blockage
  • Treating conditions that cause blockage or reflux
  • Treating infections in the urinary system

Some causes of hydronephrosis resolve without treatment, such as pregnancy and kidney stones.

Treatment options include:

  • Antibiotics to treat urinary tract infections
  • Medications to reduce excess uric acid excretion
  • Bladder catheter to drain the urine
  • Nephrostomy — a tube in your midsection that drains urine from the kidney
  • Surgery to remove a blockage or correct a defect
  • Surgery to remove part or all of the kidney

Symptoms of Hydronephrosis

If symptoms occur, they may include:

  • Pain in the back, waist, lower abdomen or groin
  • Persistent pain with urination
  • Increased urge to urinate or urinary incontinence
  • Incomplete urination
  • Fever
  • Nausea and vomiting
  • Unexplained itching

Diagnosing Swollen Kidneys

Your doctor may examine your pelvis or rectum to feel for blockages. Your doctor may also want to run these tests:

  • Urine tests
  • Blood tests
  • Bladder catheterization
  • Abdominal ultrasound
  • Intravenous urogram
  • Computed tomography angiography (CTA)
  • MRI scan
  • Cystoscopy
  • Voiding cystourethrogram

Content was created using EBSCO’s Health Library. Edits to original content made by Rector and Visitors of the University of Virginia. This information is not a substitute for professional medical advice.