title: [Characteristics of encrustation of ureteric stents in patients with urinary stones].
abstract: BACKGROUND
  The goal of this prospective study was to characterize ureteral stents encrustation in stone formers.
  
  
  METHODS
  We report the results of a study based on 658 double-J stents (412 men and 246 women) collected from patients with in situ urinary calculi. The mean age was 48.2+/-16.0 years without differences between genders. Ureteral stent encrustation was analysed by infrared spectroscopy. Results are expressed according to the main component.
  
  
  RESULTS
  The mean indwelling time was 73.5+/-73.2 days. The main component in stent encrustations was calcium oxalate (43.8%), essentially the monohydrate form (27.1%), followed by proteins (27.4%), calcium phosphates (16.4% with 8.4% brushite), and uric acid (5.2%). Struvite, detected on 49 stents, was the main component in 2.4% of cases. Significant differences according to gender and age were found: calcium oxalate monohydrate, which represented 24.5% in 20 to 29 years old men class increased to 37.0% in 50 to 59 years class and then decreased in older patients. Calcium oxalate dihydrate increased with age up to 70 years in women while it felt dramatically in man beyond 50 years old. Brushite was more abundant in young men (20.4% in patients aged 20-29 years) and was decreasing beyond this age while it remained in stable proportion for all age classes in women. Increasing prevalence of uric acid encrustations with age was observed, especially in men beyond the age of 70 years. Mineral encrustations increased with the indwelling time, the part of mineral being preponderant after 15 days: 7,3% of the stents had become massively encrusted within 113 days mean period. The comparison between biomaterials showed that silicone stents were significantly less encrusted than polyurethane stents.
  
  
  CONCLUSIONS
  Stent encrustation constitutes a serious complication of ureteral stent use in stone formers. Lithogenic factors should be considered for the prevention of stent encrustation in these patients.
authors.affiliation: Service de biochimie A, groupe hospitalier Necker-Enfants-Malades, France, 149, rue de Sèvres, 75743 Paris cedex 15, France.
authors.forename: H
authors.initials: H
authors.lastname: Bouzidi
authors.forename: O
authors.initials: O
authors.lastname: Traxer
authors.forename: B
authors.initials: B
authors.lastname: Doré
authors.forename: J
authors.initials: J
authors.lastname: Amiel
authors.forename: H
authors.initials: H
authors.lastname: Hadjadj
authors.forename: P
authors.initials: P
authors.lastname: Conort
authors.forename: M
authors.initials: M
authors.lastname: Daudon
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002129:Calcium Oxalate / Q000032:analysis; D002130:Calcium Phosphates / Q000032:analysis; D005260:Female; D006490:Hemostatics / Q000032:analysis; D006801:Humans; D017616:Magnesium Compounds / Q000032:analysis; D008297:Male; D008875:Middle Aged; D010710:Phosphates / Q000032:analysis; D011140:Polyurethanes / Q000009:adverse effects; D011446:Prospective Studies; D011506:Proteins / Q000032:analysis; D012307:Risk Factors; D012737:Sex Factors; D012828:Silicones / Q000009:adverse effects; D013055:Spectrophotometry, Infrared; D015607:Stents / Q000009:adverse effects*; D000069877:Struvite; D014514:Ureteral Calculi / Q000737:chemistry; D014527:Uric Acid / Q000032:analysis; D014545:Urinary Calculi / Q000737:chemistry* / Q000628:therapy; D014546:Urinary Catheterization / Q000295:instrumentation*
chemical_list: D002130:Calcium Phosphates; D006490:Hemostatics; D017616:Magnesium Compounds; D010710:Phosphates; D011140:Polyurethanes; D011506:Proteins; D012828:Silicones; D002129:Calcium Oxalate; D014527:Uric Acid; D000069877:Struvite