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About hydronephrosis

Hydronephrosis is a condition that occurs when a kidney swells and can't get rid of pee (urine) like it should. This swelling typically happens when urine cannot drain out from the kidney to the bladder due to a blockage or obstruction. Hydronephrosis can occur in one or both kidneys. Over time, kidney function can decrease, leading to possible kidney damage.

Signs and symptoms

Often, hydronephrosis does not cause any symptoms. Although sometimes there may be signs, which can include:

  • Pain in the lower back, side, or belly
  • Needing to pee a lot or having a hard time peeing
  • Seeing blood in your pee
  • Nausea
  • Fever


Hydronephrosis is usually caused by another underlying illness or risk factor. Causes of hydronephrosis include, but are not limited to, the following illnesses or risk factors:

  • Kidney stones
  • Congenital blockages (a defect that is present at birth)
  • Blood clots
  • Scarring of tissue (from injury or previous surgery)
  • Tumors or certain kinds of cancer (examples include bladder, cervical, colon, or prostate)
  • Enlarged prostate (noncancerous)
  • Pregnancy
  • Urinary tract infection (or other diseases that cause inflammation of the urinary tract)


In cases of severe blockage due to hydronephrosis, extra urine may need to be removed using either a catheter to drain urine from the bladder or a special tube called a nephrostomy that drains urine from the kidney. The key to treatment is to get it addressed as soon as possible in order to avoid any permanent damage to the kidneys.

Severe hydronephrosis can damage the kidneys and lead to kidney failure. If kidney failure occurs, treatment will be needed with either dialysis or a kidney transplant. When treated quickly, most people recover from hydronephrosis.


Hydronephrosis is diagnosed by:

  • Talking to the patient and doing a physical check-up
  • Having blood and urine tests
  • Using machines (like ultrasound, CT scans, MRI, or even a special telescope called a cystoscope) to take pictures of the kidneys and bladder to locate the blockage


When treating hydronephrosis, doctors try to stop the kidney from swelling further. In order to do this, they may:

  • Prescribe medicines to ease pain and/or fight off infection
  • Recommend a surgical procedure to remove the blockage

Preparing for your appointment

When getting ready to see the doctor, it's good to:

  • Write down any symptoms, like pain or frequent peeing
  • Make a list of all other health issues and medicines taken
  • Bring any test results or medical records you may have to the appointment


Questions to ask

  • What's causing my symptoms?
  • What tests do I need?
  • What treatments are there?
  • What are the side effects of treatment?
  • Will I need surgery, and if so, what will it be like?
  • Will this affect my kidneys in the long run?
  • Should I change anything about my lifestyle?
  • How can I stop hydronephrosis from happening again?


This content is provided for informational use only and is not intended as medical advice or as a substitute for the medical advice of a healthcare professional.

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