Giant ureteral stone associated with partial ureteral duplication.

We are presenting a 36-year-old male patient with right flank pain and a history of recurrent urinary tract infection for three years. Radiographic intervention revealed a right partial ureteral duplication with a giant stone in size 9.6 cm in the ureteral limb draining the non-functioning upper pole of the right kidney. Open ureterolithotomy and partial nephroureterectomy was performed by a right flank incision. The presence of a ureteral partial duplication created a "yo-yo phenomenon", which interfered with stone passage to the bladder and may cause such giant ureteral stone.