[Spontaneous migration of a metal clip into renal pelvis after laparoscopic pyeloplasty: a case report].

Migration of surgical materials into the urinary tract is very rare. We present a case of spontaneous migration of a metal clip into renal pelvis after laparoscopic pyeloplasty. A 44-year-old woman who had a long history of multiple sclerosis presented with symptomatic left hydronephrosis due to ureteropelvic junction (UPJ) obstruction. Since antegrade endopyelotomy was unsuccessful, the patient underwent laparoscopic Anderson-Hynes pyeloplasty. The UPJ was wrapped with thick inflammatory tissue and a crossing vessel that firmly adhered to the UPJ was found and dissected. Metal clips were used for hemostasis. Although the hydronephrosis was improved and flank pain was completely dissolved, a stone was identified in the pelvis 22 months after the surgery. The stone was formed around a metal clip that had been possibly migrated into the renal pelvis. Transureteral lithotripsy was performed using an 8F ureterofiberscope and a clip was removed.