Retroperitoneal fibrosis (RPF), also known as Ormond’s disease, is a rare condition in which excessive fibrous tissue develops in the retroperitoneum — the space in the abdomen behind the peritoneum (the lining of the abdominal cavity). This fibrous tissue can cause inflammation and fibrosis (scarring) of the retroperitoneal structures, including the kidneys, ureters, blood vessels, and other organs located in the retroperitoneal space.