Erosion of embolization coils into the renal collecting system mimicking stone.

Urinary tract interventions can lead to multiple complications in the renal collecting system, including retained foreign bodies from endourologic or percutaneous procedures, such as stents, nephrostomy tubes, and others. We report a case of very delayed erosion of embolization coils migrating into the renal pelvis, acting as a nidus for stone formation, causing mild obstruction and finally leading to gross hematuria roughly 18 years post transarterial embolization. History is significant for a remote unsuccessful endopyelotomy attempt that required an urgent embolization.