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  • Cynthia M. Johnson, MA
Publication Type:




Hydronephrosis is a backup of urine in one or both kidneys. This leads to swelling and pressure in the tube that connects the bladder and kidneys. It needs care right away.


Hydronephrosis happens when urine cannot drain from the kidney to the bladder. It may be caused by a blockage from:

Urinary Tract Blocked By a Stone.

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Risk Factors

Things that may raise the risk of hydronephrosis are:

  • Having any of the health problems that cause the condition
  • Cancer treatments
  • Neurogenic bladder


Some people do not have symptoms. Those who do may have:

  • Pain in the back, waist, lower belly, or groin
  • Problems urinating, such as:
    • Pain
    • Urgency
    • Urinating more or less than usual
    • A bladder that does not feel emptied after passing urine
  • Fever
  • Nausea and vomiting


The doctor will ask about symptoms and health history. A physical exam will be done. You may need to see a doctor who treats kidney diseases.

Blood and urine tests will be done to look for problems with how the kidneys are working.

Pictures of the kidneys may be taken. This can be done with:

A cystoscopy may also be done. It uses a lighted scope to view the bladder.

Other tests will be done to find a cause.


The cause of hydronephrosis will need to be treated. This will allow urine to flow as it should. Some options are:

  • Fixing defects in the kidney
  • Removing a kidney stone that will not pass on its own
  • Medicines to treat infection or ease pain
  • Inserting a tube to drain excess urine
  • Taking out of all or part of the kidney (rare)


The risk of hydronephrosis may be lowered by managing health problems that can harm the kidneys.





  • Hydronephrosis. Cleveland Clinic website. Available at: https://my.clevelandclinic.org/health/diseases/15417-hydronephrosis.
  • Hydronephrosis. National Kidney Foundation website. Available at: https://www.kidney.org/atoz/content/hydronephrosis.
  • Hydronephrosis. NHS Choices website. Available at: https://www.nhs.uk/conditions/hydronephrosis.
  • Nephrolithiasis in adults. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/nephrolithiasis-in-adults-24.
  • Nuraj, P and Hyseni, N. The diagnosis of obstructive hydronephrosis with color doppler ultrasound. Acta Inform Med. 2017 Sep; 25(3): 178–181.
  • Obstructive uropathy. Merck Manual Professional Version website. https://www.merckmanuals.com/professional/genitourinary-disorders/obstructive-uropathy/obstructive-uropathy.


  • Mark S. Itzkowitz, MD, JD
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.