title: Flushing of the vagina and the prepuce-a cause for contaminated urine cultures in children.
abstract: An uncontaminated urine culture is a prerequisite for the diagnosis of a urinary tract infection. However, this may be difficult to obtain in small children. We have studied the frequency of ballooning of the prepuce in non-circumcised boys and vaginal reflux in girls during voiding as a possible cause of contaminated urine cultures.
  
  
  
  All micturating cystourethrograms (MCUG) performed in our institution over the last 5 years in children aged 0-15 years were reviewed retrospectively for ballooning of the foreskin or vaginal reflux as a potential source of bacterial contamination. The voiding pictures were routinely done with the catheter present for the first voiding cycle and then removed on the second void.
  
  
  
  A total of 526 children (77.4 % boys, 22.6 % girls) were eligible for the study. Ballooning of the foreskin was identified on the micturition pictures of 115 (38 %) boys, with the frequency significantly higher in boys aged <12 months [odds ratio (OR) 4.1; 95 % confidence interval (CI) 2.1-7.3)] and boys with vesicoureteral reflux (OR 1.6; 95 % CI 1.06-2.4). Seventeen girls (14.3 %) showed vaginal reflux. No correlation with age or vesicoureteral reflux was found in the girls.
  
  
  
  Ballooning of the prepuce or vaginal reflux was seen on a fluoroscopic MCUG in a large proportion of children during their voiding. This normal phenomenon might cause contaminated urine cultures when the urine is obtained by bag or clean catch.
authors.affiliation: Nephrology Unit, Great Ormond Street Hospital for Children, WC1N 3JH, London, UK. kjell.tullus@gosh.nhs.uk.
authors.forename: Kjell
authors.initials: K
authors.lastname: Tullus
authors.affiliation: Department of Pediatric Nephrology, Ali Asghar Children Hospital, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Nakysa
authors.identifier: 0000-0002-8494-947X
authors.initials: N
authors.lastname: Hooman
authors.affiliation: Department of Radiology, Great Ormond Street Hospital for Children, WC1N 3JH, London, UK.
authors.forename: Marina
authors.initials: M
authors.lastname: Easty
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D052816:Foreskin / Q000382:microbiology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012189:Retrospective Studies; D016482:Urinalysis; D014546:Urinary Catheterization; D014552:Urinary Tract Infections / Q000175:diagnosis / Q000382:microbiology; D014554:Urination; D014556:Urine / Q000382:microbiology*; D014621:Vagina / Q000382:microbiology*; D014718:Vesico-Ureteral Reflux / Q000382:microbiology*
keywords: Ballooning of prepuce; Physiological phimosis; Urinary tract infections; Vaginal reflux