Pinball calculus in a ureterosigmoidostomy.

We report a complication during the treatment of lithiasis with extracorporeal shock wave lithotripsy in a patient with a ureterosigmoidostomy. This woman presented with renal colic bilaterally and renal insufficiency and was found to have an extremely mobile calculus. A significant gaseous reflux from the sigmoid colon was found to propel the solitary calculus in a retrograde fashion across the ureteroileal anastomosis up the ureter into one kidney, and then later, after re-descent to the level of the anastomosis, up into the opposite kidney. After several days of playing hide and seek with this migrating calculus, using extracorporeal shock wave lithotripsy, the patient became stone free.