title: Pilot study of ureteral movement in stented patients: first step in understanding dynamic ureteral anatomy to improve stent comfort.
abstract: OBJECTIVE
  Ureteral stents may cause significant morbidity, including pain, dysuria, hematuria, and infection. New biomaterials, coatings, and designs have been studied in an attempt to reduce stent-related symptoms, but to date, the ideal comfortable stent has not been developed. In order to facilitate development of a stent that will mold and change with patient movement, we examined stent and ureteral movement with changes in patient body position.
  
  
  METHODS
  Four women and two men with a median age of 60.5 +/- 7.7 years who underwent shockwave lithotripsy and insertion of a ureteral stent were enrolled. Static radiographs were performed with the patients in four positions: supine, standing, sitting, and bending forward. Differences in stent position were analyzed digitally relative to fixed bony reference points to determine ureteral movement.
  
  
  RESULTS
  The renal stent curl was most cephalad when the patient was supine and moved caudally an average of 2.5 +/- 1.5 cm when the patient stood up. The absolute vertical length of the stent was greatest when the patient was supine (31.1 +/- 1.2 cm) and shortened with standing (28.3 +/- 2.3 cm) and sitting (26.6 +/- 1.5 cm). The bladder curl moved an average of 2.3 +/- 1.2 cm vertically with patient movement.
  
  
  CONCLUSIONS
  By measuring stent position, we were able to quantify the range of motion of the ureter during changes in body position. Stent movement appears to be a combination of bowing in the proximal ureter and moving within the bladder. Future stent designs may take this into account to decrease stent-related symptoms.
authors.affiliation: Division of Urology, University of Western Ontario and St. Joseph's Health Care, London, Ontario, Canada. ben.chew@vch.ca
authors.forename: Ben H
authors.initials: BH
authors.lastname: Chew
authors.forename: Bodo E
authors.initials: BE
authors.lastname: Knudsen
authors.forename: Linda
authors.initials: L
authors.lastname: Nott
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Pautler
authors.forename: Hassan
authors.initials: H
authors.lastname: Razvi
authors.forename: Justin
authors.initials: J
authors.lastname: Amann
authors.forename: John D
authors.initials: JD
authors.lastname: Denstedt
mesh_terms: D000368:Aged; D001672:Biocompatible Materials; D004867:Equipment Design; D005260:Female; D006801:Humans; D007668:Kidney / Q000473:pathology / Q000503:physiopathology*; D008096:Lithotripsy; D008297:Male; D008875:Middle Aged; D009403:Nephrostomy, Percutaneous / Q000295:instrumentation / Q000379:methods*; D010865:Pilot Projects; D011187:Posture; D015607:Stents; D014513:Ureter / Q000473:pathology*; D018666:Ureteroscopy / Q000379:methods
chemical_list: D001672:Biocompatible Materials