Hydronephrosis is another word for swelling of 1 or both kidneys. The kidneys are organs in the urinary tract that make urine. Each kidney has 2 parts:

  • A part that filters the blood and removes waste and excess salt and water
  • A part that collects the urine

In hydronephrosis, the part of the kidney that collects the urine gets too much urine in it. This makes it swell and get bigger than normal.

Hydronephrosis happens when the urinary tract gets blocked. Then the urine can’t drain, and it backs up into the kidney. Different conditions can cause a blockage in the urinary tract.

In adults, the most common causes of a blockage are:

  • Benign prostatic hyperplasia, or “BPH” – This is the medical term for an enlarged prostate. The prostate is an organ (in men) that surrounds the urethra. The urethra is the tube the urine goes through before leaving the body.
  • Cancer of the prostate or cancer of other organs in the lower belly – Cancer growths can push on the urinary tract to block the flow of urine.
  • “Stones” in the urinary tract – Small “stones” can form from the salts and minerals that are normally in the urine. These stones can block the urinary tract.

Blockages can happen suddenly or slowly over time. They can affect 1 or both kidneys.

Some people with hydronephrosis have no symptoms, especially if the blockage happened slowly over time. They might find out they have hydronephrosis when their doctor does a test for another reason.

When people do have symptoms, they usually include:

  • Pain – People can have pain in their lower belly, genital area, sides, or lower back.
  • Changes in urination – Hydronephrosis usually makes people urinate less than usual. But this doesn’t always happen.

People can have other symptoms, too, depending on what is causing the blockage. For example, if the hydronephrosis is caused by BPH, symptoms might include:

  • Needing to urinate often
  • Having trouble starting to urinate
  • Having a weak urine stream, or leaking or dribbling urine
  • Feeling as though the bladder is not empty after urinating

Yes. If you have the symptoms listed above, call your doctor or nurse. If you are not able to urinate at all, call them right away.

Yes. Your doctor or nurse will ask about your symptoms and do an exam. They will also do tests to check for the cause of your hydronephrosis and see how serious your condition is. These tests can include:

  • Blood tests
  • Urine tests
  • Different types of imaging tests – Imaging tests create pictures of the inside of the body.

You might not need any treatment if you have no symptoms, your blood test results are normal, and your kidneys are working normally.

If you do need treatment, it will depend on your individual situation.

To help urine drain out of your urinary tract, your doctor might put tubes in different parts of your urinary tract.

If your blockage has caused an infection in your urinary tract, your doctor will also prescribe antibiotics to treat the infection.

Your doctor will also remove the blockage in your urinary tract. How your doctor does this will depend on what is causing the blockage. For example, BPH that causes hydronephrosis is usually treated with surgery to remove some of the prostate or shrink the prostate.

If cancer is causing your hydronephrosis, your doctor will talk with you about your treatment options. Cancer can be treated in different ways, depending on the type of cancer.

Stones in the urinary tract can be treated with:

  • A machine that uses sound waves to break up the stones
  • Surgery to remove the stones
  • A procedure called “ureteroscopy” in which a doctor puts a thin tube into the urethra. The tube has special tools on the end that the doctor can use to break up or remove the stones.