title: Resonance metallic stents do not effectively relieve extrinsic ureteral compression in pediatric patients.
abstract: OBJECTIVE
  Use of metallic stents (Resonance) has been reported in the literature to be effective in relieving extrinsic obstruction in adults. Successful patency rates have been reported to be around 83.3%. The use of Resonance stents in children has not been reported. We present our experience with these stents in addressing extrinsic ureteral obstruction in the pediatric population.
  
  
  METHODS
  We identified two patients who underwent placement of Resonance stents for extrinsic compression at the Children's Hospital of the University of Pittsburgh Medical Center. The first patient is a 12-year-old girl with a solitary left kidney who had a diagnosis of pelvic rhabdomyosarcoma; she was treated with surgery followed by adjuvant chemoradiation. Two years post-treatment, worsening renal function secondary to ureteral strictures developed. The second patient is a 14-year-old girl with a history of Gardner syndrome. Recurrent desmoid tumors developed in her pelvis and retroperitoneum that led to right ureteral obstruction, necessitating a nephrostomy tube.
  
  
  RESULTS
  Both patients underwent successful technical placement of a Resonance stent. The time to failure for patient 1 was 3 months and for patient 2, 3 weeks. The first patient presented to the emergency department 3 months poststent in renal failure with a creatinine level of 13.7 mg/dL. This necessitated nephrostomy tube placement and hemodialysis. Ultimately, she needed an ileal ureter to preserve renal function. She is off hemodialysis and has a creatinine level of 2.2 mg/dL.The second patient, recurrent episodes of pyelonephritis, worsening hydronephrosis, and flank pain developed with just the Resonance stent in place. It was elected to remove the Resonance stent and replace the nephrostomy tube. She needed extensive ureterolysis, a right subtotal ureterectomy with a right to left ureteroureterostomy.
  
  
  CONCLUSIONS
  We did not find the use of these stents to be effective in children. The time to failure was significantly shorter in children than those reported in the literature for adults.
authors.affiliation: Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA. bishoy.gayed@utsouthwestern.edu
authors.forename: Bishoy A
authors.initials: BA
authors.lastname: Gayed
authors.forename: Abhijith D
authors.initials: AD
authors.lastname: Mally
authors.forename: Julie
authors.initials: J
authors.lastname: Riley
authors.forename: Michael C
authors.initials: MC
authors.lastname: Ost
mesh_terms: D000293:Adolescent; D002648:Child; D003251:Constriction, Pathologic; D005260:Female; D006801:Humans; D008670:Metals / Q000627:therapeutic use*; D015607:Stents; D017211:Treatment Failure; D014517:Ureteral Obstruction / Q000601:surgery*
chemical_list: D008670:Metals