title: Study on concretions developed around urinary catheters and mechanisms of renal calculi development.
abstract: OBJECTIVE
  To study the structure and composition of encrustation and concretions developed on urinary catheters to better understand their formation mechanism to be able to prevent them.
  
  
  METHODS
  The surface of catheters was studied by direct and scanning electron microscopy observation. In vitro formation of encrustations was performed in synthetic urine.
  
  
  RESULTS
  The surface of catheters was covered by a continuous layer of organic matter, on which a thin scale consisting of crystals of calcium oxalate monohydrate (COM), uric acid anhydrous or calcium phosphate developed. Encrustations observed on catheters generally exhibited the same composition as the previously developed renal calculi. In catheters collected from patients without previous episodes of renal calculi or with previous episodes of infected renal calculi in which infection was afterwards eradicated, on the first organic layer, in that case plate-like COM crystals forming a columnar layer were observed. In vitro experiments demonstrated that COM columnar structures were only formed when normocalciuric urine containing organic matter was used, and the presence of crystallization inhibitors, as phytate, notably delayed their formation.
  
  
  CONCLUSIONS
  Calcium oxalate was the main crystalline phase developed on catheters inserted in patients, specially in the absence of urinary infection or urinary pH values <5.5 and high urinary uric acid levels. Thus, prophylaxis of encrustations may consist of preventive measures usually applied in cases of recurrent idiopathic calcium oxalate urolithiasis.
authors.affiliation: Laboratory of Renal Lithiasis Research, Faculty of Sciences, University Illes Balears, Palma de Mallorca, Spain. dqufgf0@ps.uib.es
authors.forename: F
authors.initials: F
authors.lastname: Grases
authors.forename: O
authors.initials: O
authors.lastname: Söhnel
authors.forename: A
authors.initials: A
authors.lastname: Costa-Bauzá
authors.forename: M
authors.initials: M
authors.lastname: Ramis
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D002129:Calcium Oxalate / Q000737:chemistry / Q000652:urine; D002408:Catheters, Indwelling / Q000009:adverse effects; D003460:Crystallization; D005260:Female; D006801:Humans; D006882:Hydroxyapatites; D066298:In Vitro Techniques; D007669:Kidney Calculi / Q000209:etiology* / Q000652:urine; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D012212:Rheology / Q000295:instrumentation; D014546:Urinary Catheterization
chemical_list: D006882:Hydroxyapatites; D002129:Calcium Oxalate