Migration of a ureteric calculus to the bladder via a ureterocolic and a vesicocolic fistula.

Following a difficult nephrectomy for pyonephrosis, two large calculi in the left pelvic ureter were not removed. The upper of these two calculi finally found its way into the bladder after ulcerating into the sigmoid colon and thence into the bladder. The calculi and the residual ureter were removed and the fistulae closed, with a successful outcome.