Retroperitoneal fibrosis is a rare disorder in which the tubes (ureters) that carry urine from the kidneys to the bladder are blocked by a mass in the area behind the stomach and intestines.

Retroperitoneal fibrosis is a rare disorder that occurs when extra fibrous tissue forms in the area behind the stomach and intestines. The excess tissue forms a mass (or masses) that can block the tubes that carry urine from the kidney to the bladder. Doctors don't know why these masses form. It is most common in people aged 40 - 60. Men are twice as likely to develop the condition as women.

Early symptoms:

• Dull pain in the abdomen that increases with time
• Pain and change of color in the legs (due to decreased blood flow)
• Swelling of one leg

Later symptoms:

• Decreased urine output
• No urine output (anuria)
• Nausea, vomiting, changes in thinking caused by kidney failure and build-up of toxic chemicals in the blood
• Severe abdominal pain with hemorrhaging (due to death of intestinal tissue)

Abdominal CT scan is the best method to reveal a retroperitoneal mass.

Other tests that can help diagnose this condition include:

• BUN and creatinine blood tests
• Intravenous pyelogram (IVP)
• Kidney ultrasound
• MRI of the abdomen

A biopsy of the mass may also be done to rule out cancer.

Powerful anti-inflammatory medicines called corticosteroids are tried first. Some doctors also use a drug called tamoxifen to treat this condition.

If corticosteroid treatment doesn't work, a biopsy should be done to confirm the diagnosis. If confirmed, other medicines to suppress the immune system are usually prescribed.

When medicine does not work, surgery and stents (draining tubes) are needed.

Prognosis depends on the extent of the fibrosis and the amount of damage to the kidneys. The kidney damage may be temporary or permanent.

The disorder may lead to:

• Chronic bilateral obstructive uropathy
• Chronic kidney failure
• Chronic unilateral obstructive uropathy

Call your health care provider if you experience lower abdomen or flank pain, particularly with decreased urine volume.

If possible, avoid long-term use of medications that contain methysergide, which has been shown to cause retroperitoneal fibrosis. Methysergide is sometimes used to treat migraine headaches.

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