Hello Thanks for query ..Based on the facts that you have posted it seems you have been diagnosed to have Retro Peritoneal Fibrosis . This is disease caused by unknown etiology which causes inflammation and fibrosis in retro peritoneal tissue and gradually involves the organs like kidney and ureter giving rise to flank pain and obstruction to flow of urine from kidney in to bladder. The objective in managing this disease is to maintain kidney function by decompressing the kidney which was attempted by putting stents in ureter for many times. In view of unknown etiology many medications have been tried with uncertain results . The best alternate is to undergo surgery of Uroterolysis where ureter is freed from the fibrous tissue and to maintain flow of urine from kidney in to bladder. Dr.Patil.