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Medically reviewed by Last updated on Mar 5, 2023.

Hydronephrosis is swelling in one or both kidneys caused by urine buildup. Urine normally flows from the kidneys to the bladder through tubes called ureters. A blockage in the ureters can prevent urine from flowing properly. Urine flow may also be prevented or slowed if your kidneys do not work correctly. Urine flows back into your urinary tract. Pressure builds up in the kidney and causes swelling.



Informed consent

is a legal document that explains the tests, treatments, or procedures that you may need. Informed consent means you understand what will be done and can make decisions about what you want. You give your permission when you sign the consent form. You can have someone sign this form for you if you are not able to sign it. You have the right to understand your medical care in words you know. Before you sign the consent form, understand the risks and benefits of what will be done. Make sure all your questions are answered.


  • Antibiotics help treat or prevent an infection caused by bacteria.
  • Pain medicine may be given before your treatment. Do not wait until the pain is severe before you ask for more medicine.


  • Blood tests show if your kidneys are working properly or have a blockage.
  • Urine tests show how much urine your body is removing. They may also show if you have infection, blood, or protein in your urine. This may mean your kidneys are not working as they should.
  • X-rays may be taken of your kidneys, bladder, and ureters. You may need to have dye injected into your kidneys before the x-ray to help healthcare providers find the blockage. Tell the healthcare provider if you have ever had an allergic reaction to contrast dye.
  • An ultrasound may be used to show the size of your kidneys or bladder, and if they are swelling.
  • Abdominal CT may be used to show the exact location of the blockage.


  • An IV is a small tube placed in your vein that is used to give you medicine or liquids.
  • A renal diet is a meal plan that includes foods that are low in sodium (salt), potassium, and protein. Your healthcare provider may also tell you to eat and drink more vegetables and juices.
  • Stone removal procedures may be used to remove the kidney stones that are slowing or blocking your urine flow. Your healthcare provider may perform surgery to remove the stones. Strong sound waves called shock wave therapy may be used to break up large kidney stones. This will help make them small enough for you to pass them when you urinate.
  • Catheter or stent placement may be needed to help increase your urine flow. You may need a catheter (flexible tube) placed directly into your bladder to drain urine. Your healthcare provider may place a hard plastic tube called a stent inside your urinary tract to help urine pass from your kidney to your bladder.
  • Surgery may be needed to remove part or all of your kidney if it is not working properly. Your prostate may need to be removed if it is so large that it is blocking urine flow.


Swelling in one or both kidneys from too much urine buildup may lead to long-term kidney damage. Partial blockages may cause loss of urine control. Severe hydronephrosis may cause a blood infection called sepsis. Sepsis is toxin (poison) buildup in your blood. It happens when your kidneys cannot flush toxins out of your body. It could also paralyze your intestines. Your kidneys could fail without treatment. These conditions may be life-threatening.


You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your healthcare providers to decide what care you want to receive. You always have the right to refuse treatment.

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The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

Further information

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