Hydronephrosis is the result of a problem in the urinary tract. Urine drains from the kidneys into the bladder. With hydronephrosis, urine backs up into the kidneys causing a buildup of pressure.

Urinary Tract Blocked By a Stone

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Causes of hydronephrosis:

  • Kidney stones
  • Blood clots
  • Growths or tumors
  • Scarring—can happen from an accident or surgery
  • An enlarged prostate
  • Urine can't drain into the bladder
  • Bladder is not draining well
  • Pregnancy

Risk Factors

Your risk is higher if you have:


Some people don't have symptoms. If symptoms appear, they may cause:

  • Pain in the back, waist, lower belly, or groin
  • Problems related to urination:
    • Pain
    • Urgency
    • Lower output
    • Cycles of lower and higher output
    • Bladder not feeling emptied out
  • Fever
  • Nausea or vomiting


The doctor will ask about your symptoms and health history. You may also have:


The goal of care is to treat the cause. This will help ease pressure and limit further problems.

Care may involve:

  • Fixing structural defects
  • Treating a kidney stone
  • Placing a stent—a tube is used to keep a passage open
  • A tube is placed into the kidney to drain urine— nephrostomy
  • Taking out of all or part of the kidney (rare)— nephrectomy


If you have problems with your kidneys, getting prompt care will lower your chances of complications.


National Institute of Diabetes and Digestive and Kidney Diseases

National Kidney Foundation


Health Canada

The Kidney Foundation of Canada


Hydronephrosis. Cleveland Clinic website. Available at: Updated March 18, 2014. Accessed June 5, 2018.

Hydronephrosis. National Kidney Foundation website. Available at: Accessed June 5, 2018.

Hydronephrosis. NHS Choices website. Available at: Updated June 23, 2015. Accessed June 5, 2018.

Nephrolithiasis. EBSCO DynaMed Plus website. Available at: Updated February 5, 2018. Accessed June 5, 2018.

Obstructive uropathy. Merck Manual Professional Version website. Updated March 2018. Accessed June 5, 2018.

Last reviewed May 2018 by EBSCO Medical Review Board Adrienne Carmack, MD  Last Updated: 6/5/2018