A urinoma is a collection of urine that forms in the space where your abdominal organs sit. It usually develops when you have a condition that has led to urinary obstruction. Instead of flowing out of your urethra as it should, urine flows back into your retroperitoneum, the space inside your abdomen.


What is a urinoma?

A urinoma is a collection of urine (pee) that forms in the retroperitoneum. The retroperitoneum is the space in the body where your abdominal organs sit. It's behind the peritoneum, the tissue that lines your abdominal wall and covers most of the organs there, such as your intestines, stomach, liver and bladder.

Urinomas form when pee flows irregularly, entering the retroperitoneum and combining with fat. They usually form because of a blockage that causes some of the pee to flow backward, leaking into the retroperitoneum.


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How does the urinary system work?

When you eat, your body takes in the energy and nutrients it needs, then leaves behind waste products. Your urinary system eliminates the liquid waste products through pee. In a functioning urinary system:

  1. Your kidneys filter toxins from your blood and create pee.
  2. Pee flows from the kidneys to tubes called ureters.
  3. The ureters connect to the bladder, which stores pee.
  4. When you urinate, pee exits your bladder through a tube-like structure called the urethra.

Where does a urinoma occur?

Urinomas form in the retroperitoneum, the back portion of your abdomen.

What is extravasation of urine?

Extravasation of urine refers to when pee doesn’t flow as it should. Instead of exiting the body through the urethra, some of it collects in other body cavities, such as the retroperitoneum.


Symptoms and Causes

What are the symptoms of a urinoma?

People with a urinoma may feel a noticeable mass in their abdomen. They may also experience:

What causes a urinoma?

Urinomas usually occur because of a condition that causes a urinary obstruction, such as:

Urinomas may also develop after surgery on your abdominal organs or urinary system.


Diagnosis and Tests

How is a urinoma diagnosed?

Your healthcare provider uses tests to diagnose a urinoma, including:

  • CT scans, using computers and X-rays to get pictures of the inside of your body.
  • Fluoroscopy, using continuous X-rays to create an “X-ray movie” to see inside your body.
  • MRIs, using magnets and radio waves to see your organs and soft tissues in detail.
  • Ultrasounds, using high-frequency sound waves to see inside your body.

Management and Treatment

How can I reduce my risk of a urinoma?

There’s no guaranteed way to prevent a urinoma. But you can reduce your risk of a urinary obstruction by practicing healthy bladder habits. You may:

Outlook / Prognosis

What can I expect if I have a urinoma?

Many urinomas are small and don’t interfere much with your daily activities. Larger urinomas are often the result of an underlying condition that causes a urinary obstruction. Many people don’t have further problems with urinomas after they receive treatment for the underlying condition.

Living With

What questions should I ask my doctor?

If you have a urinoma or think you could, you may also want to ask your healthcare provider:

  • What is the most likely cause of a urinoma?
  • Do I have an underlying condition that led to a urinoma?
  • What tests do I need to diagnose a urinoma?
  • What are the treatment options for a urinoma?
  • What are the chances that a urinoma will develop again after treatment?

A note from Cleveland Clinic

A urinoma is a collection of urine that forms in the back of your abdomen. It usually develops because of urinary obstruction. Urinomas form when your pee doesn’t flow out of the urethra as it should. Instead, some pee flows back into the retroperitoneum. Small urinomas usually don’t need any specific treatment. Your healthcare provider may drain a large urinoma and treat any underlying condition that caused it.

Medically Reviewed

Last reviewed on 08/29/2022.

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