title: Bladder stone formation after sigmoidocolocystoplasty: statistical analysis of risk factors.
abstract: OBJECTIVE
  Bladder stone formation (BSF) after sigmoidocolocystoplasty (SCP) is a major source of morbidity. The authors identify risk factors and analyze them statistically.
  
  
  METHODS
  Medical records of 106 patients who had SCP at our institute were reviewed to examine the incidence of post-SCP BSF, the stone removal method and length of follow-up. The primary underlying pathological conditions were myelomeningocele in 103 patients and other conditions in 3. Risk factors for BSF were statistically assessed by comparing cases with and without BSF.
  
  
  RESULTS
  Bladder stone formation occurred in 20 (18.9%) of 106 patients (BSF group). The remaining 86 did not have stones (NBSF group). Mean age at SCP was 11.7 years in the BSF group and 10.2 years in the NBSF group. Mean follow-up was 12.0 years in the BSF group and 11.0 years in the NBSF group. BSF developed after a mean of 30.3 +/- 25.6 months after SCP. Twenty-two stone removal procedures were performed in the BSF group and spontaneous evacuation occurred in 4 instances. Once stone free, BSF recurred in 4 patients. Although differences between the 2 groups with respect to sex, age at SCP, follow-up period, bladder capacity, bladder compliance, incidence of gram-negative bacteriuria, incidence of gram-positive coccus bacteriuria, electrolytes, frequency of urinary catheterization, post-SCP incidence of vesicoureteric reflux, and incidence of ureteric reimplantation were not statistically significant, differences in the incidence of spontaneous micturition, bladder neck tightening procedures, or gram-positive bacillus bacteriuria, or frequency of bladder irrigation were all statistically significant (P < .05 in all, Fisher's Exact test).
  
  
  CONCLUSIONS
  The authors are the first to statistically analyze a wide range of varying risk factors for BSF. BSF would appear to be common after SCP.
authors.affiliation: Department of Pediatric General and Urogenital Surgery, Juntendo University School of Medicine, Tokyo 113-8421, Japan.
authors.forename: Hongbo
authors.initials: H
authors.lastname: Zhang
authors.forename: Atsuyuki
authors.initials: A
authors.lastname: Yamataka
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Koga
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Geoffrey J
authors.initials: GJ
authors.lastname: Lane
authors.forename: Takeshi
authors.initials: T
authors.lastname: Miyano
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D012809:Colon, Sigmoid / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D012307:Risk Factors; D013524:Surgical Flaps; D001743:Urinary Bladder / Q000601:surgery*; D001744:Urinary Bladder Calculi / Q000209:etiology*; D014546:Urinary Catheterization; D016055:Urinary Retention / Q000150:complications* / Q000628:therapy; D013520:Urologic Surgical Procedures