title: Prevalence of nephrolithiasis in patients with ileal bladder substitutes.
abstract: OBJECTIVE
  To assess the effect of ileal bladder substitutes with preservation of the ileocecal valve and distal 25 cm of ileum on nephrolithiasis.
  
  
  METHODS
  We reviewed a consecutive series of 518 patients (44 women and 474 men) with ileal orthotopic bladder substitution in whom 55 to 65 cm of ileum was resected but with preservation of the ileocecal valve and distal 25 cm of ileum, to determine prevalence of nephrolithiasis as well as bicarbonate, base excess, creatinine levels, and urinary pH at time of stone diagnosis and 2 years before it.
  
  
  RESULTS
  Four male patients with a median age of 66 years (range, 50 to 70 years) developed nephrolithiasis after ileal bladder substitute, for a total of five calculi. The prevalence of nephrolithiasis in this retrospective cohort is thus 1% (5 of 518). They developed the calculi after a median follow-up of 8 years (range, 4 to 17 years). The four patients were diagnosed with calculi at 2.3, 3, 10, 10.3, and 14 years after bladder substitute. Two of the stones were uric acid calculi; the remaining three were calcium oxalate. None of our patients were acidotic or had elevated serum creatinines at time of stone formation. Urinary pH determined once in spontaneously voided urine at the time of stone diagnosis was pH 6.0 for the two uric acid calculi and pH 7.0 for the remaining calculi.
  
  
  CONCLUSIONS
  The present study demonstrates a low prevalence of calculi in our cohort.
authors.affiliation: Department of Urology, University of Bern, Switzerland.
authors.forename: Nivedita Bhatta
authors.initials: NB
authors.lastname: Dhar
authors.forename: Adrian V
authors.initials: AV
authors.lastname: Hernandez
authors.forename: Karsten
authors.initials: K
authors.lastname: Reinhardt
authors.forename: Gianluca
authors.initials: G
authors.lastname: Giannarini
authors.forename: Pascal
authors.initials: P
authors.lastname: Zehnder
authors.forename: Roger M
authors.initials: RM
authors.lastname: Müller
authors.forename: Urs E
authors.initials: UE
authors.lastname: Studer
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D007082:Ileum / Q000637:transplantation; D008096:Lithotripsy; D008297:Male; D008875:Middle Aged; D053040:Nephrolithiasis / Q000453:epidemiology* / Q000503:physiopathology / Q000628:therapy; D011183:Postoperative Complications / Q000453:epidemiology; D015995:Prevalence; D019651:Plastic Surgery Procedures; D012189:Retrospective Studies; D016476:Urinary Reservoirs, Continent