Temporary or permanent diversion of the flow of urine through the ureter away from the urinary bladder in the presence of a bladder disease or after cystectomy. There is a variety of techniques: direct anastomosis of ureter and bowel, cutaneous ureterostomy, ileal, jejunal or colon conduit, ureterosigmoidostomy, etc. (From Campbell's urology, 6th ed, p2654)