DefinitionRetroperitoneal 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.Alternative NamesIdiopathic retroperitoneal fibrosis; Ormond's diseaseCauses, incidence, and risk factorsRetroperitoneal 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.SymptomsEarly symptoms:Dull pain in the abdomen that increases with timePain and change of color in t