title: Therapy-resistant nephrolithiasis following renal artery coil embolization.
abstract: BACKGROUND
  Transcatheter renal artery embolization is an effective and minimally invasive treatment option for acute renal bleeding. Early post-interventional complications include groin hematoma, incomplete embolization, coil misplacement and coil migration. Late complications are rare and mostly related to coil migration.
  
  
  METHODS
  A 22-year-old woman with a history of recurrent stone disease and a lumbal meningomyelocele underwent bilateral open pyelolithotomy for bilateral staghorn calculi. Post-operatively, acute hemorrhage of the left kidney occurred and selective arterial coil embolization of a lower pole interlobular renal artery was performed twice.Four years after this intervention the patient presented with a new 15.4 mm stone in the lower calyx of the left kidney. After two extracorporeal shock wave lithotripsy treatments disintegration of the stone was not detectable. Therefore, flexible ureterorenoscopy was performed and revealed that the stone was adherent to a partially intraluminal metal coil in the lower renal calyx. The intracalyceal part of the coil and the adherent stone were successfully removed using the holmium laser.
  
  
  CONCLUSIONS
  Therapy-resistant nephrolithiasis was caused by a migrated metal coil, which was placed four years earlier for the treatment of acute post-operative renal bleeding. Renal coils in close vicinity to the renal pelvis can migrate into the collecting system and trigger renal stone formation. Extracorporeal shock wave lithotripsy seems to be inefficient for these composite stones. Identification of these rare stones is possible during retrograde intrarenal surgery. It also enables immediate stone disintegration and removal of the stone fragments and the intraluminal coil material.
authors.affiliation: Department of Urology, University Hospital Zürich, University of Zürich, Frauenklinikstrasse 10, 8091 Zürich, Switzerland. cedric.poyet@usz.ch
authors.forename: Cédric
authors.initials: C
authors.lastname: Poyet
authors.forename: Florian
authors.initials: F
authors.lastname: Grubhofer
authors.forename: Matthias
authors.initials: M
authors.lastname: Zimmermann
authors.forename: Tullio
authors.initials: T
authors.lastname: Sulser
authors.forename: Thomas
authors.initials: T
authors.lastname: Hermanns
mesh_terms: D000328:Adult; D020878:Device Removal / Q000379:methods*; D004621:Embolization, Therapeutic / Q000009:adverse effects* / Q000295:instrumentation*; D005260:Female; D005548:Foreign-Body Migration / Q000209:etiology* / Q000628:therapy*; D006801:Humans; D008096:Lithotripsy; D053040:Nephrolithiasis / Q000209:etiology* / Q000628:therapy*; D017211:Treatment Failure; D016896:Treatment Outcome